Note: Descriptions are shown in the official language in which they were submitted.
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METHODS FOR PERFORMING INTELLIGENT NETWORK SERVICIr;S
WITH AN ISDN NETWORK TERMINATOR LOCATED AT
A SUBSCRIBER'S PREMISE
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates genes°ally to telecommunication call processing
for a telephone
subscriber and more particularly to a network terminator based arrangement
located at a subscriber's
premise for performing call waiting, caller identification, call conferencing,
call forwarding and dual
digital device communication sharing on one S-bus.
Description of Related Art
ISDN is defined by internationally accepted standard digital network user
interfaces. The
resulting network offers a variety of subscriber access lines capable of
supporting services including
voice, data, facsimile, and video. There are two International Telegraph and
Telephone Consultative
Committee (CCITT) recommended standard integrated services digital network
interfaces for user
access. They include a basic rate interface (BRI) and a primary rate interface
(PRI). By integrating
these various services on a single transport system means, the subscriber
avoids buying multiple
services to meet multiple service needs. As a practical consideration a single
transport system
2 0 requires less overhead than providing a discrete access line for each
service, and results in a total
lower cost of service.
An ISDN Basic Rate Interface (BRI) consists of tin-ee channels, referred to as
two B channels
plus a D channel (2B + D), in which all signals flowing over the external
telephone company (telco)
lines are carried in a baseband digital Porn and in a standardized frame
format. With this
2 5 arrangement, the B channels are the basic user channels which carry
digital voice, high-speed data,
and other functions at a maximum channel rate of 64kbps. The D channel bit
rate in this interface
is 16 kbps and may serve two purposes. First, the D channel carries control
signalling information
to control circuit-switched calls on associated B channels at the user
interface. In addition, the D
channel may be used for packet switching or low speed telemetry when not
carrying signalling
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information. Accordingly, an ISDN Primary Rate lntertuce consists of multiple
B channels and one
64 kbps D channel having primary rates of either 1544 kbps (23B + D) or 2048
kbps (3t)8 + D).
The BRI may be arranged to provide simultaneous voice and data services in
several ways
giving users flexibility in configuring their services. A user may use each B
channel for voice
service, for circuit switched data transport, or for packet switched data
services. The D channel can
carry packet switched data which interleaves data packets with signalling
packets. The BRI may
provide a maximum of either two data B channels or one voice B channel and
another voice or data
channel.
Typically, a single line subscriber premise is wired with two discrete pairs
of wires,
sometimes referred to as plain old telephone service (POTS). In the POTS
configuration, one pair
of signal wires provides a communication path between analog terminal
equipment and a junction
box that interfaces to external telco wiring. Another pair of signal wires
provides a second, or spare,
path between analog terminal equipment and the external junction box.
Although ISDN networks are widely used in current telecommunication systems,
coexistence
between analog and digital terminal equipment at a customer premise on a
single subscription line
has heretofore been impractical. As one solution, discrete digital and analog
classes of service to the
subscriber premise are provided ire order to otter support to both analog and
digital devices. Thus,
when a single line subscriber elects to add ISDN service, a junction box
connection that interfaces
to external telco wiring typically remains tixed, hut internal POTS wiring is
either bypassed or
2 0 elaborately moditled in order to provide a communication path for digital
ISDN signals if only ones
pair of pre-existing wires exist.
As an alternative solution, a single line subscriber may elect to convert from
an analog to a
digital class ofservice. In that scenario, the subscriber premise is converted
to accommodate digital
terminal equipment only. In so doing, the subscriber is compelled to scrap pre-
existing conventional
2 5 telephone (POTS) wiring and tenvinal eduipment, which had effectively
become useless, in order
to maintain a single (digital) class of service. The desirable solution is
disclosed in earlier filed
United States Patent Number. 5,448,631, tiled June 30, 1993 and owned in
common with this
invention. This application discloses an architecture and apparatus tbr
connecting both analog and
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digital devices in a subscriber premise to a single subscription line in an
ISDN network, using
existing POTS wiring in the premises.
A disadvantage to an ISDN subscriber arises from various types of class
services (e.g., call
forwarding, call waiting, caller II)) which are currently handled by the
central office switching
system and require the user to pay additional charges for their use. An ISDN
network includes an
ISDN central office switching system which is connected to communication
devices) located at a
subscriber's premise via the subscriber's telephone line. A computer is
connected to the switching
system which transmits to the computer associated messages corresponding to
call handling
information exchanged between the switching system amd the user telephone
stations connected
thereto.
In operation, various types of class services (e.g., call forwarding, call
waiting, caller ID) are
handled by the central office switching system by transmitting call handling
messages (e.g., SETUP,
ALERTING, CONNECT, D1SCONNEC"T) from the switch to the user station and vice-
versa. The
interface between the switch and the station is typically the basic rate
interface (2B + D). Since class
services cur-ently require processing by the central office switch, the user
incurs an additional charge
by the telco for these services.
Another disadvantage to a subscriber arises when a digital class of service is
used and more
than one digital communication device is connected to a single S-bus at the
subscriber's premise.
According to current standards for Layer 'I char~~cteristics of ISDN user-
network interfaces (CCITT
Recommendation I.430), only one digital communication device can be active
during a
communication session. For example, in a subscriber premise having at least
two digital telephone
stations connected to a single S-bus, after a subscriber has picked up a
receiver of one of the stations
no other receiver can be used to talk on the same phone conversation.
A further disadvantage results from the lack of a basic electronic key
telephone service
2 5 (EKTS) for analog phones. Digital telephones currently operate with EKTS
and call appearance call
handling (CACH) EKTS standards provided by the ISDN network. The digital EKTS
phones have
numerous buttons and display lights (or a digital display) to allow a user to
perforn functions such
as call conferencing, call hold!retrieve, etc. and the lights or display are
used to indicate to the user
that these features have been activated. E-towever, there is no such EKTS
facilities used for analog
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telephones. In addition, since the network terminator described in US Patent
No. 5,488,645 will
couple analog devices to the ISDN network, there is a need to develop a user
interface for allowing
a user to perform functions such as call confcrencing and call holdiretrieve
on an analog telephone
coupled to ISDN EKTS serv-ice.
Accordingly, it is an object of the present invention to provide a
subscriber's premise with
a network terminator based arrangement which can utilise the B-channels of an
ISDN network to
perform call waiting, caller identification, call conferencing, call
forwarding and communication
sharing on one S-bus with more than one digital communication device. It is a
further object of the
present invention to provide these call processing functions to digital and/or
analog devices at the
subscriber's premise. It is yet a further object ofthe present invention to
provide a user interface for
mapping actions performed on an analog telephone into EK'rS signals recognised
by an ISDN
network. It is another object of the present invention to provide a single
line communication path
between digital and analog devices at a subscriber's premise and an ISDN
network through existing
POTS wiring.
SUMMARY OF THE INVENTION
The present invention is directed to a network terminator (adapter) based
arrangement located
at a subscriber's premise which can be connected to a digital telephone
network and can perform
various call processing functions without the requirement of intervention from
a telco switch. The
2 0 network adapter includes a processor which can perform digital signal
prc:~cessing functions in
accordance with the present invention. The adapter is operatively coupled to
the digital network and
a communication device at the subscriber's premise.
One embodiment of the present invention is directed to a call processing
method which
implements call waiting in the network adapter based arrangement. The method
includes the step
of establishing a first wall cm a communication device at the subscriber's
premise on a first
communication channel. Next, in response to a deternination that a second call
is being made to the
subscriber's premise, the adapter will connect the second call on a second
communication channel.
If the subscriber's premise does not include a second ccnnmunication device
coupled to the
second communication channel, then after connecting the second call on the
second communication
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channel, the adapter will send a private alerting signal to the user (e.g.,
beeps). Next, the program
will enter a loop whereby the user will have the option to toggle between the
first and second calls
indefinitely until a disconnect request is made from any of the parties to the
call. By connecting the
two calls on the two communication channels and toggling between them at the
user's option, the
adapter eliminates the need for intervention ti-om the telco switch to perform
call waiting.
Another embodiment of the present invention is directed to a call processing
method which
implements caller identification (ID) in the network adapter based arrangement
without the need for
a separate caller ID box. The method includes the step of receiving a call
SETUP message from a
switching system specifying an incoming call to the subscriber's premise. The
call SETUP message
contains information on the identity of the number initiating the call. After
determining that caller
ID is activated at the subscriber's premise and that the receiver has been
picked up, the adapter will
extract a first message identifying the call from the call SETUP message.
Next, the processor within
the adapter will voice synthesize the first message to the receiver such that
the subscriber will hear
an identifying message. The identifying message can be the number of the
incoming caller.
Alternatively, the adapter can be provided with a preprogrammed lockup table
having a
plurality of numbers each of which having a corresponding name. Before vaice
synthesizing the
identifying number to the receiver the adapter can determine whether the
identifying number
matches any one of the plurality of numbers in the lockup table. In response
to a determination that
the identifying number matches any one of the plurality of numbers, the
adapter will voice
2 0 synthesize the name to the receiver. In response to a determination that
the identifying number does
not match any one of the plurality of numbers, the adapter will voice
synthesize the identifying
number to the receiver.
After hearing the identifying information (number or name of caller) the
subscriber has the
option of accepting or rejecting the call. If the user chooses to accept the
call, the adapter will
2 5 connect it to an available communication channel. If the user decides not
to receive the call, the
adapter will continue to return a ringing signal to the caller and return to
an idle state.
A further embodiment of the present invention is directed to a call processing
method for
conferencing up to three calls from a communication device at the subscriber's
premise using the
network adapter based arrangement of the present invention. The method
includes the step of
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establishing a first call on the communication device at the subscriber's
premise on a first
communication channel. The next step is to initiate from the communication
device a call setup
request to establish a second call. After the second call is accepted, the
adapter will connect the
second call on a second communication channel. Next, the adapter will
establish a three way
communication path between the communication device and the tirst and second
calls by mixing
voice data on said first communication channel with voice data on said second
communication
channel such that each person can listen to each other.
The voice mixing is performed by the processor within the adapter. The local
vc>ice signal
of one B-channel (B 1 ) is copied downstream of B 1 to the upstream of the
other B-channel (B2)
while the local voice data signal of B2 is copied downstream of B2 to the
upstream of B1. This
automatically establishes a three way conference call and allows each of the
parties to communicate
with each other. This voice mixing of the two B-channels by the processor will
continue until a
disconnect request is made by any one of the parties to the conference call.
By connecting each of
the calls to a separate communication channel and voice mixing the two
channels, the adapter
eliminates the need for the Telco's switching system to conference the calls.
Another embodiment of the present invention is directed to a call processing
method of
forwarding a call made to a first communication device at the subscriber's
premise to an alternate
destination utilizing the network adapter based arrangement. The method
includes the step of
receiving at the adapter a message: from a switching system specifying an
incoming call to the
2 0 subscriber's premise. Next, the adapter wil I initiate a first connection
on a first communication
channel between the first communication device and a second communication
device at the alternate
destination. After the first connection is established, the incoming call is
connected to the first
communication device on a second communication channel.
Next, the processor will establish a communication path between the incoming
call and the
2 5 alternate destination by mixing voice data on the tirst communication
channel with voice data on the
second communication channel such that a voice communication path is
established by the adapter
between the incoming call and the alternate; destination. The processor will
continue voice mixing
until a disconnect request is made ti-om the incoming caller or the alternate
destination. The method
according to this embodiment removes the Telco switch from performing call
forwarding.
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In each of the above described embodiments the digital network can be an
Integrated Services
Digital Network (ISDN) and the first and second communication channels can be
ISDN B-channels
of~ a basic rate interface. 'The communication device at the subscriber's
premise can be either an
analog or a digital device.
In another embodiment of the present invention. dash hook and touch tone
commands allow
a user to perform call holdiretrieve, call waiting and three way call
conferencing functions on an
analog telephone coupled to an ISDM network via the network terminator of the
present invention.
In addition, if multiple call appear~nnces are provided by the telco, then up
to a six way conference
call can be established with the analog phone. Each of these call conferencing
functions are
pcrfonned on one B-channel according to E:1<TS standards. The analog signals
(switch hook and
touch tone commands) input by a user to the analog phone are converted to ISDN
EKTS signals by
a telephone interface within the adapter c7f the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates a schematic overview of a communication wiring scheme and
network
adapter utilized in accordance with the methods of the present invention.
Fig. 2 is a block dia~~ram illustrating a network adapter based implementation
of a call
processing arrangement in accordance with the present invention.
Fig. 3 is a block diagram illustrating a modular interconnect bus used in the
network adapter
2 0 according to the present invention.
Fig. 4 is a block diabn-am illustrating a telephone interface used in the
network adapter
according to the present invention.
Fig. 5 is a flow chart of a call processing program used for call waiting in
the adapter based
implementation of Fig. ?.
2 5 Fig. 6 is a partial flow chart of an alternative embodiment of the call
processing program of
Fig. 5.
Fig. 7 is a flow chart of a call processing program used for caller
identification in the adapter
based implementation of F ig. 2.
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Fig. 8 is a tlow chart of a call processing program used for call conferencing
in the adapter
based implementation of Fig. 2.
Fig. 9 is a tlow chart of a call processing program used for call forwarding
in the adapter
based implementation of Fig. 2.
Fig. 10 is a flow chart of a call processing program used to establish
intercommunication
between two digital communication devices coupled to an S-bus in the adapter
based implementation
of Fig. 2.
Fig. 1 1 is a switch hook state table for an analog telephone coupled to an
ISDN network via
the adapter of the present invention showing a current state along with the
state resulting from each
of three dash hook activities.
DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 illustrates an arrangement for linking both analog and digital devices
to a single
subscription line in an ISDN network, using pre-existing telephone wires 24,
:26. This arrangement
serves a number of functions (some of which will be more particularly
described hereinafter) and
is more fully disclosed in co-pending, earlier tiled United States Patent No.
5,448,635, tiled June 30,
1993 and owned in common with this invention.
The wiring in a subscriber premise comprises four signal wires. These wires
extend to a
junction box 2 that connects the customer premise to an ISDN carrier network.
Inside the premise,
2 0 these wires terminate at modular telephone jacks 4 located in the walls of
the subscriber premise.
A Green-Red (G-R) pair of wires 24 is coupled to analog terminal equipment
such as communication
devices 6 (e.g., telephone equipment), while a Black-~'elluw pair of wires 26
is coupled to the ISDN
digital carrier network. Telco carrier network wiring at the junction box 2 is
connected to the pair
of wires 26 and isolated from the pair ofwires 24.
2 5 A network adapter 10 is plugged into any wall jack 8. The network adapter
10 serves as an
interface between two wire subscriber loop signals on wires 26 in a
standardized digital form, and
an S-bus 22 through which digital devices 12 (e.g., digital telephone
equipment, fax machine, etc.)
are connected. The digital and analog interface network adapter 10 also serves
as an interface
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between two wire subscriber loop signals on wires 26, in the standardized
digital form, and analog
devices that connect to the G-R wire pair 24 via other wall jacks 4 (jacks
other than jack 8).
The B-Y wire pair 26 is adapted at the junction box 2 to interface with the
Telco ISDN
carrier network. Likewise, the G-R wires <rre "'open" at the junction box but
connected uniformly to
analog devices. The wiring change at the.junction box 2 may be adapted by
manually changing the
wires at the junction box 2.
With the arrangement as described in Fig. l, the S-bus wiring can be provided
with a (usually
short) cable extending from network adapter 10 to digital equipment located
near the adapter 10
(usually one device or set of devices sharing a single network port).
Accordingly, the network
adapter 10 is plugged into a modular telephone jack 8 at any desired (room,
wall) location and the
telco carrier interface is adapted as shown. The S-bus shown need not extend
through any walls if
all digital devices are in the same room as the adapter. However, the wiring
scheme may require
extended (additional) S-bus wiring for additional digital devices and terminal
adapters.
With this arrangement, all signals tlowing between the external telco carrier
network and the
customer premise are channelled through the network adapter 10 (via the
internal B-Y pair 26 and
the inside jack 8 to which the network adapter 10 is connected). All signals
flowing between the
network adapter 10 and digital devices run through the S-bus 22 interface
between the network
adapter 10 and the digital devices. All signals flowing between the network
adapter 10 and any
analog device run through the R-G pair 24 between the jack 8, at which the
network adapter 10 is
2 0 connected and another jack 4, at which the analog device is connected.
It should be understood that with this ar-r-angement, signals flowing between
any analog
device and the external carrier network pass in analog form through the R-G
pair linking the jack 4,
at which the analog device is connected, to the adapter 10; get converted in
the adapter 10 between
analog and two wore digital ISDN forms; and pass in the latter form between
the adapter 10 and the
external carrier network, via the internal B-Y pair of wires 26 and the
junction box 2. Signals
flowing between any digital device and the external telco lines pass in
digital form between the
device and the adapter 10 via the S-bus 2'?; get converted in the adapter 10
between four wire S-bus
digital form and two wire digital ISDN; and pass in the latter form between
the adapter 10 and the
external carrier network, via the B-Y pair 26 and the junction box 2.
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Fig. 1 illustrates internal wiring at the subscriber premise configures as a
single loop. With
the single loop configuration, analog devices may be connected to the junction
box 2 at any one of
the modular telephone jacks 4 along the loop. It should be understood that
alternate internal wiring
configurations may be found at the subscriber premise, with another
configuration presently
contemplated being a star wiring configuration. With the star wiring
configuration, a jack 4 at any
branch of the star configuration may individually connect an analog device to
the junction box 2
(configuration not shown).
Referring now to Fig. 2, number 10 refers to the block diagram of the digital
and analog
network adapter architecture constructed according to the teachings of the
present invention. The
adapter 10 includes a system processor 30 which is connected by I/O control
lines 32 to an E2PROM
34, U interface device 36, telephone interface 38 and ISDN access controller
40. The processor 30
can be any suitable microprocessor which also performs data signal processing
functions. One
suitable microprocessor is the 803 I which is sold by INTEL.. Alternatively,
the processor 30 can be
a Digital Signal Processor (DSP) which also perfouns micruprocessing
functions. One suitable DSP
is the MWAVE MSP1.0 which is sold by IBM. A suitable U interface device 36 is
the PEB 2091;
a suitable ISDN access controller 40 is the PEB 2()70 or 2081. Each of the PEB
devices is sold by
Siemens Components, Inc.
Continuing with the description of Fig. 2, a local bus 42 further connects the
processor 30,
SRAM 44, and EPROM 46. The local bus 42 comprises conductors used for
transmitting address,
2 0 data, or control signals between interconnected devices.
Referring still to Fig. 2, modular interconnect bus 48 interconnects the U
interface 36,
telephone interface 38, and ISDN access controller 40. As seen in Fig. 3,
modular interconnect bus
48 consists of four discrete signal lines including a 8 Khz frame sync (FS)
signal line 50, data clock
(CLK) line 52, receive serial bit stream (RX) signal line 54, and a transmit
serial bit stream (TX)
2 5 signal line 56. While modular interconnect bus 48 serves to connect the U
interface 36, telephone
interface 38, and ISDN access controller 40, bus 48 may also be used to
connect other diverse
voice/data modules (sources or targets for the D channel, or sources or
targets for the B 1 and B2
channels).
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The U interface device 36 is further connected to an input transformer 58
through a hybrid
60. The input transformer 58 is connectable to one pair of "through-connected"
pre-existing
telephone wires 26 within the subscriber premise and acts as a transformer and
driver to the
telephone network. As such, the "through connected" pair of telephone wires 26
is operatively
connected to the telephone network but not coupled to any analog devices
within the subscriber
premise. The pair of wires 26 may be the B-Y pair, according to the typical
POTS configuration, as
described.
Thus, a signal coming ti-om the Tclco network is first adapted at transformer
58 for input to
the hybrid 60, where the signal is split into discrete transmit and receive
signals. Partial cancellation
of local echo and correct impedance matching to a four wire input for the U
interface 36 is further
performed by hybrid 60.
The U interface 36 further conditions the incoming signal by performing echo
cancellation
and equalization on the four wire digital signals received, and converts the
signals into a TTL level
binary stream which contains digital information. The echo cancellation with
hybrid (ECH) principle
is one which supports full duplex operation over a two wire subscriber Ioop.
The ECH method and
resultant TTL level binary stream are in conformance with ANSI standard
T:1.601.
In the preferred embodiment, the network adapter architecture 10 has, been
configured to
interface with a BRI ISDN. Call processing of B-channel and D-channel data is
performed
according to CCITT spec Q.931 protocol which comprises processing carrier
network and adapter
2 G 1 (> functions for both incoming and outgoing calls. Call processing of B-
channel data with adapter
10 for analog and digital devices is described in more detail in copending
United States Patent
Application Serial No. 085,333 mentioned above. The LJ intertuee 36 is ofthe
type to accommodate
a 2B 1 Q, or other standard digital channelizcd torn as required by the local
telephone network. For
2 B 1 Q line coding, for example, pairs of bits are represented as one of four
quantum levels. This is
2 5 a four level pulse amplitude modulation (PAM) code without redundancy.
The; coded signal is a two
wire subscriber loop signal characterized as having a frequency spectrum which
is lower than the
frequency spectrum of an uncoded digital signal. The two wire subscriber loop
signal offers reduced
line attenuation and crosstalk over the ISDN. In so doing, an 80K.hz 2B 1 Q
two wire subscriber loop
BOC9- I 994-0024CA5 l 1
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signal at the U interface 36 may be converted into two discrete 160 Khz
signals (transmit and
receive).
The ISDN access controller 40 is connected by S-bus interface 62 to S-bus 22.
Interface 62
comprises a four wire interface at the S-bus 22 for connecting one or more
digital devices within the
subscriber premise. S-bus interface 62 contains a four wire transformer that
supports up to eight
digital devices according to the ANSI Tl .60~ standard.
The telephone interface 38 i s further connectable by analog hybrid 64 to the
other pair of pre-
existing telephone wires 24 within the subscriber premise. The other pair of
pre-existing telephone
wires 24 is operatively connected to analog devices within the subscriber
premise; e.g., the G-R pair
in the typical POTS configuration, as described. The other pair of pre-
existing telephone wires 24,
as distinguished from the first pair of pre-existing wires 26, is connected
only to existing analog
devices within the subscriber premise (at jacks other than jack 2A). In the
preferred embodiment,
the analog hybrid 64 is a subscriber line interface circuit providing drive,
on-hook, and off-hook
functions to the analog devices and telco network.
As shown in Fig. 4, the telephone interface 38 comprises a subscriber line
interface circuit
39 which accepts commands such as for example., switch hook commands such as
off hook, on-
hook, flash, etc. that are interpreted by the processor 30 via interrupts. The
interface circuit 39 also
accepts touch tone commands that are interpreted by a dual tone multiple
frequency (DTMF)
detector 41. An audio ringing codes tilter 43 under control oi~the processor
30 generates tones and
2 0 performs digital to analog conversions of the signals to be sent to the
communication device via the
interface circuit 39. A suitable subscriber line interface circuit 39 is the
HC-5504B sold by Harris
Corporation; a suitable DTMI~ detector 41 is the MC' 145436 sold by Motorola;
a suitable audio
ringing codes filter is the PSB 2160 sold by Siemens Components, Ine.
The interface circuit 39, DTMF decoder 41 and filter 43 are used to convert
analog signals
2 5 (including switch hook and touch tone commands entered by a user on an
analog phone) into ISDN
signals such as electronic key telephone service (EKTS) or call appearance
call handling (CACH)
EKTS signals. More specifically, signals flowing between any analog device and
the external ISDN
network pass in analog fore through the analog hybrid 64 and telephone
interface 38; get converted
BOC9-1994-0024CA5 12
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in the telephone interface 3~ between analog and two wire digital ISDN forms
such as EKTS; and
pass in the latter form to the 1SDN network via U-interface 36 and hybrid 60.
It is to be understood that elements in network adapter 10 are connectable to
both pairs of
pre-existing telephone wires 24, 26 through any modular telephone jack 8. That
is, a single plug
serves to connect the network adapter 10 to both the carrier network and
analog devices.
System processor 30 controls its internal operation as well as interfacing
with other elements
of the network adapter 10. It should be understood by those skilled in the art
of the present invention
that the processor 30 will perform power on diagnostics and initial program
load routines before
beginning execution of any of the call processing programs described below.
The power on
diagnostics and initial program load are well known routines. Each ofthe call
processing programs
described below are stored in EPROM 46 and loaded into SRAM 44 during the
initial program load
routine for execution by the processor 30.
Referring now to Fig. 5, there is illustrated a flow chart including the basic
process steps used
by processor 30 in executing a call processing program which implements call
waiting in the
network adapter based arrangement in accordance with the present invention
when one
communication device is coupled to both B-channels of a BRI. The coding of the
process steps of
this l7ow chart into the instructions suitable to control the processor 30
will be r.rnderstandable to one
having ordinary skill in the art of programming.
After performing initial program load and power on diagnostic routines, the
processor 30
2 0 enters the IDLE state indicated at block 100. As shown in block 1 O5,
program execution begins
either in response to a call SETUP message initiated by communication device 6
at the subscriber's
premise for an outgoing call or in response to receipt by communication device
6 of a call SETUP
message for an incoming call from a Telco ISDN switch. Execution proceeds to
block 1 10 where
the processor 30 checks whether the first: call has been established. Block
110 represents
conventional handshaking whereby the communication device 6 and the ISDN
switch are
exchanging call handling messages such as SETUP AC'K, ALERTING, CONNECT, etc.
During
block 1 10, if the call is not established (e.g., a busy line), the NO branch
is taken from block 110 to
block 115 where the call is rejected and a busy signal is returned to the
communication device 6.
Next, the processor 30 returns to the IDLE block 100.
BOC9-1994-0024CA5 ~ 3
CA 02412725 2002-12-19
Referring back to block 110, when a call is established the YES branch is
taken form block
l 10 to block 120 where the first call is connected to a first B-channel of a
Basic Rate Interface.
Execution proceeds to block 125 where a check is made to determine whether a
DISCONNECT call
request has been made from either party to the first call, and ifit has, the
YES branch is taken fiom
decision block 125 to block 130 to end the call and release the B-channel.
'hhe system will then
return to the idle state at block I 00, If no disconnect request is made,
execution proceeds from block
125 to block 135 where a check is made to determine whether a call SETUP
message is being
transmitted by the ISDN telco switch for stn incoming call whip the first call
is still active. If there
is no setup request for an incoming call, the NO branch is taken from block
135 back to block 125.
Thus, it can be seen that when one call is active the system will remain in a
loop between blocks 125
and 135 while waiting fc~r either an incoming call setup request or a request
to disconnect the first
call.
Referring back to block 13_5, if a call SETUP message is received by
communication device
6 for an incoming call, the YES branch is taken from block 135 to decision
block 140. At decision
block 140 the processor 30 checks whether the second B-channel is busy. If the
second B-channel
is busy, then the YES branch is taken from decision block 140 to block 145
where the call is
rejected, abusy signal is returned to the caller making the incoming call and
the processor 30 returns
to decision block 125. The processor 30 returns to block 125 because there is
still one active call
connected to the first B-channel.
2 0 At block 140 if the second B-channel is not busy then the NO branch is
taken to block 150
where the incoming call (second call) will be ec~nnected to the second B-
channel. Execution
proceeds to block 155 where a private alerting signal (e.g., a beep) is sent
to the receiver of the
subscriber's communication device 6. The subscriber will then have an option
to receive/not receive
the second call by togglinginot toggling between the first and second calls as
shown at block 160.
2 5 The toggling can be performed by for example, depressing the flash button
on the receiver of device
6. If the subscriber decides to toggle and receive the second call, the YES
branch is taken from block
L60 to block 165 where the subscriber's cc:~mtnunication device fi will be
connected to the second B-
channel by processor 30 to allow the subscriber to communicate with the secund
caller. Execution
then proceeds to decision block 170.
BOC9-1994-0024CA5 (.t
CA 02412725 2002-12-19
If the subscriber chose not to toggle at block I 60, execution will proceed
directly from block
160 to decision block 170 where a check is made to determine whether a
disconnect request is made
to disconnect one of the B-channels. The disconnect request may arise from
either of the three parties
on the two calls. If a disconnect is requested from either party to the first
or second call, the YES
branch is taken fronn block 170 to block 175 where the corresponding B-channel
is released.
Execution then proceeds to block 125 and continues as described above. If a
disconnect message is
nut received, the processor 30 proceeds from block 170 to block l 80 where it
checks whether a third
call SETUP message is being transmitted by the ISDN Telco switch for an
incoming call. If a third
SETUP request is received, the YES branch is taken from block 180 to block 185
where the third
call is rejected and a busy signal is returned to the communication device
making the third call. The
third call is rejected since both B-channels c>f the BR I are active with a
call. Execution then proceeds
back to decision block 160 and continues as described above.
If a third call SETUP message was not received, execution will proceed
directly from block
180 to block 160 and continue as described above. The logic resulting from
blocks 160, 165, 170,
180 and 185 allows the subscriber to toggle indefinitely between the tirst and
second calls until a
disconnect message is made from either end of the first ur second calls
(subscriber included).
Referring to Fig. 6, there is shown an alterm:~tive embodiment of the call
waiting pro~,~ram of
the present invention. In this embodiment, all steps up to block 150 are
identical to that described
above with regard to Fig. 5. In this embac~liment, the subscriber has a first
communication device
2 0 connected to the first B-channel and a second communication device
connected to the second B-
channel of a BRI. The first and second communication devices can be two analog
devices 6 or two
digital devices 12.
After connecting the incoming call to the second B-channel, execution proceeds
tcom block
150 to block 152 where an alerting signal is sent to the second communication
device. Execution
2 5 proceeds to decision block 154 where the subscriber has the option to
accept/not accept the second
call. At block 154, the processor 30 checks whether the subscriber has
accepted the second call (i.e.,
receiver on second device taken oft hook 1. If the subscriber chooses not to
accept the call, the NO
branch is taken from block 154 to block l 25 where execution proceeds as
described above. If the
subscriber chooses to accept the call then the YES branch is taken to block
156 where a check is
BOC9-1994-0024CA5 I 5
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made to determine whether a disconnect request is made by any of the parties
to disconnect one of
the calls. If a disconnect is requested ti-orn either party to the first or
second call, the YES branch
is taken from block 156 to block l SS where the corresponding B-channel is
released. Execution then
proceeds to block 125 and continues as described above.
If a disconnect message is not received, the processor 30 proceeds from block
156 to block
162 where it checks whether a third call SETUP message is being transmitted by
the ISDN Telco
switch for an incoming call. If a third SETUP request is received, the YES
branch is taken from
block 162 to block 164 where the third call is rejected and a busy signal is
returned to the
communication device making the third call. Execution then proceeds back to
decision block 156
and continues as described above. If a third call SETUP message was not
received, execution will
proceed directly from block 162 to block 156 and continue as described above.
By connecting the two calls an the two B-channels of a BRI and allowing the
subscriber to
accept (toggle between calls when only one device is coupled to the BRI or
pickup the receiver of
a second device when each of two devices are coupled to one B-channel, the
adapter 10 eliminates
the need for intervention from the Telco switch to perform call waiting at the
subscriber's premise.
Referring now to Fig. 7, there is ill ustrated a flow chart including the
basicprocess steps used
by processor 30 in executing a call processing program which implements caller
identit3cation in the
network adapter based arrangement in accordance with the present invention.
Again, the coding of
the process steps of this flow chart into the instructions suitable to control
the processor 30 will be
2 0 understandable to one having ordinary skill in the art of programming.
After performing initial program load and power on diagnostic routines, the
pracessor 30
enters the IDLE state indicated at block 200. Program execution begins in
response to receipt by
communication device 6 of a call SETU f' message for an incoming call from the
ISDN switch as
shown at block 205. The SETUP message includes calling party identity
information, e.g., a phone
2 5 number of the calling party. Next, decision block 2 l 0 is entered where a
check is made to determine
whether caller ID is activated at the subscriber's premise. If caller ID is
not activated, the call is
conventionally processed and connected to one of the B-channels as indicated
at block 215. If caller
ID is activated, execution proceeds to block 220 where the processor 30 will
indicate to the
subscriber that a call is coming through by generating an alerting signal on
the communication
BOC9-1994-0024CA5 ~ c~
CA 02412725 2002-12-19
device 6. Next, execution proceeds to check whether the receiver of the
communication device 6 has
been picked up (taken off hook) as shown at Mock 225. M'he program remains at
block 225 until the
receiver goes off hook. If no one picks up the receiver, the receiver will
continue to ring until the
calling party hangs up.
Atter the receiver is picked up, the YES branch is taken from block 225 to
block 230 where
the processor 30 will extract the number of the incoming caller ti-om the
SETUP message received
from the ISDN switch. Execution then proceeds to block 235 where the number is
compared to
numbers in a preprogrammed look up table (LUT). The LU'f can be programmed by
the user and
contains a plurality of numbers having additional information (e.g., name,
address) associated with
each number. If the caller's number does not match any of the numbers in the
LUT, the NO branch
is taken from block 235 to block 240 where the processor 30 will voice
synthesize the number to the
phone receiver. If the caller's number does match a number in the LUT, the YES
branch is taken
froth block 235 to block 245 where the additional information (c.g., name)
which corresponds to the
number in the LUT is voice synthesized to the receiver. Execution proceeds
from block 240 or 245
to block 250 where after hearing the phone number (or additional information)
of the incoming call,
the subscriber can choose to accept the call.
At block 250, the processor 30 checks whether the subscriber chose to accept
the call. If the
subscriber chose to accept the call, a connect reduest is made and the
processor 30 connects the call
to the available B-channel as shown at block 255. Execution proceeds from
block 255 to block 260
2 0 where the processor 30 will remain until a DISCONNECT call reguest has
been made from either
party to the call. Once a disconnect message is received, the YES branch is
taken froth decision
block 260 to block 265 to end the call and release the B-channel. The system
will then return to the
idle state at block 200.
Referring back to block 250, if a connect reduest is not made, the progn-am
proceeds to block
2 5 270 where the processor 350 checks whether the subscriber chose not to
receive the call. If no
choice is made at that time, execution proceeds to block 250 and continues
therefrom as described
above. Thus, it can be seen that the program will loop within blocks 250 and
270 until the subscriber
chooses to accept or deny the incoming call. If the subscriber chooses to
reject the call, the YES
branch is taken from block 270 back to block 200 where the system returns to
the idle state. The
BOC9-1994-0024CA5
CA 02412725 2002-12-19
device which initiated the call will continue to receive a ringing signal but
the device 6 at the
subscriber's premise will no longer ring.
Thus, the network adapter 10 of the present invention eliminates the need for
a special box
for caller ID by sending a private ring to the subscriber's receiver whenever
there is an incoming call
and delivering the number as a number (block 240) or a name corresponding to
the number (block
245) in voice form to the receiver when picked up. The receiving party can
then choose whether to
accept or reject the call by depressing a key on the receiver, e.g., a short
hook flash to accept or a
long hook flash to reject the call.
Referring now to Fig. 8, there is ill ustrated a flow chart including the
basic process steps used
by processor 30 in executing a call processing program which implements call
conferencing in the
network adapter based arrangement in accordance with the present invention.
Again, the coding of
the process steps of this flow chart into the instructions suitable to control
the processor 30 will be
understandable to one having ordinary skill in the art of programming.
After performing initial program load and power on diagnostic routines, the
processor 30
enters the IDLE state indicated at block 300. As shown in block 305, progwam
execution begins
either in response to a call SETUP message initiated by coannunication device
6 at the subscriber's
premise for an outgoing call or in response to receipt by communication device
6 of a call SETUP
message for an incoming call from a Telco ISDN switch. Execution proceeds to
block 310 where
the processor 30 checks whether the first call has been established. Block 310
represents
2 0 conventional handshaking as described above with regard to block 1 10 of
Fig. 5. If the call is not
established (e.g., busy line), the NO branch is taken ti-om block 310 to block
315 where the call is
rejected and a busy signal is returned to the communication device 6. Next,
the processor 30 returns
to the IDLE block 300.
Referring back to block 310, if a call is established the YES branch is taken
ti-om block 310
2 5 to block 320 where the first call is connected to a first B-channel.
Execution proceeds to block 325
where a check is made to determine whether a DISCONNECT call request has been
made from
either party, and if it has, the 5'ES branch is taken from decision block 325
to block 330 to end the
call and release the B-channel. The system will then return to the idle state
at block 300. If no
disconnect request is made, execution proceeds from block 325 to block 335
where a check is made
BOC9-1994-0024CA5 l 8
CA 02412725 2002-12-19
to determine whether a call SETUP request is initiated by the subscriber's
communication device 6
to establish a second call. If so, the processor 30 then checks whether the
second call is accepted by
the person receiving the second call. After the second call is accepted,
execution proceeds to block
345 where the second call is connected to the second B-channel.
In the next two blocks 350 and 35s the processor 30 will mix the voice signal
of one of the
B-channels with the voice signal of the other B-channel so that each of the
three parties can listen
to each other. More specifically, in block 350 the local voice signal of one B-
channel (B 1 ) is copied
downstream of BI to the upstream of the other B-channel (B2) whip in block 355
the local voice
data signal of B2 is copied downstream of B2 to the upstream of B 1. This
voice mixing can be
summarized by the following equations:
US(B) = US(B1) + US(B2)
DS(B l ) = US(B2 ) + DS(B)
DS(B2) = US(B 1 ) + DS(B)
where US is upstream and DS is downstream. The voice mixing can be performed
utilizing
conventional digital signal processing algorithms programmed within processor
30.
This voice mixing of the two B-channels by the processor 30 will continue
until one of the
calls is disconnected from the conference call as shown by blocks 350, 355 and
360. When a request
is made from any communication on the conference call to disconnect its
respective call, the YES
branch of block 360 is taken to block 36a where the corresponding B-channel is
released by the
processor 30. Execution then proceeds to block 32~ where execution proceeds as
described above.
This method can be used to establish up to three calls on the conference call.
By connecting each
of the calls to a separate communication channel and voice mixing the two
channels, the adapter 10
2 5 eliminates the need for the Telco's switching system to conferwce the
calls.
Referring now to Fig. 9, there is illustrated a flow chart including the basic
process steps used
by processor 30 in executing a call processing program which implements call
forwarding in the
network adapter based arrangement in accordance with the present invention.
Again, the coding of
BOC9-1994-0024CA5
CA 02412725 2002-12-19
the process steps of this flow chart into the instructions suitable to control
the processor 30 will be
understandable to one having ordinary skill in the art of programming.
After performing initial program load and power on diagnostic routines, the
processor 30
enters the IDLE state indicated at block -I00. Program execution begins in
response to receipt by
communication device 6 of a call SETUP message for an incoming call from the
ISDN switch as
shown 405. Execution proceeds to block 410 where the processor 30 will
initiate call handling
messages to establish a connection on one of the B-channels between the
communication device 6
and a device at the number where the call is to be forwarded. This is done by
providing and
receiving appropriate call messages between the ISDN switch and the
communication device 6 at
the subscriber's premise such as SETUP, SETUP ACK, ALERTING, CONNECT, etc.
Execution proceeds from block 410 to decision block 415 where the processor 30
checks
whether the connection has been established between the subscriber's terminal
equipment 6 and the
terminal equipment at the forwarded location. If the call is not established
(e.g., the forwarded
number is busy), the NO branch is taken from block 415 to block 420 where the
call is rejected, a
busy signal is returned to the device which initiated the call and execution
returns to the idle state
at block 400.
Refen-ing back to block 41 _S, if the connection is established on the first B-
channel, the YES
branch is taken from block 415 to block 425 where the incoming call made to
the communication
device 6 is accepted. Next, execution prcaceeds to block 430 where the
incoming call is connected
2 0 to the second B-channel. Thus, after the processor 30 has completed the
processing steps in block
430, a first connection is established on the first B-channel between the
device 6 and the device at
the forwarded location while a second connection is established on the second
B-channel between
the device 6 and the incoming call.
Execution proceeds to blocks 435 and 440 where the processor 30 will mix the
voice signal
2 5 of the first B-channel (B l ) with the voice signal of the second B-
channel (B2) so that the party
initiating the call can communicate with the party at the forwarded location.
The voice mixing of
the two B-channels in blocks 435 and 440 is identical to the voice mixing
described above with
regard to blocks 350 and 355 of Fig. 8. By establishing the first and second
connections described
BOC9-1994-0024CA5 20
CA 02412725 2002-12-19
above on the two B-channels of a Basic Rate Interface and voice mixing the two
B-channels, the
network adapter 10 eliminates the need ti7r the Telco switch to forward the
call.
Execution proceeds ti-om block 440 to block 445 where the processor 30 checks
whether a
disconnect request is made from either party to the call. If ~~ request is
made to disconnect the
forwarded call form either end, the Y'ES branch of block 445 is taken to block
450 where both B
channels associated with the communication device 6 at the subscriber's
premise are released by the
processor 30 and execution returns the idle state as indicated at block 455.
If a disconnect request
is not made from either end, the processor 30 will check to see if a new call
setup request has been
made to the device 6 as shown at blo ck 4fi0. If a new call setup request has
not been made,
execution proceeds to blocks 435 and 44(J where data mixing continues. If a
new call setup request
is made, then the YES branch is taken from block 460 to block 465 where the
new call is rejected
and a busy signal is returned to the new calling panty. Execution then
proceeds to blocks 435 and 440
as described above. Thus, the processor 3() will loop within blocks 435, 440,
445, 460 and 465 and
continue to voice mix the two B-channels until a disconnect call request is
received from the device
which made the initial call or the device at the forwarded location.
Referring now to Fig. 10, there is illustrated a flow chart including the
basic process steps
used by processor 30 in executing o call processing pro~~ram which allows two
digital
communication devices 8 on the same S-bus 22 to share a communication session.
Again, the coding
of the process steps of this flow chart into the instructions suitable tc~
control the processor 30 will
be understandable to one having ordinary skill in tlne art of programming.
After performing initial program load and power on diagnostic routines, the
processor 30
enters the IDLE state indicated at block 500. As shown in block 505, program
execution begins
either in response to a call SETUP message initiated by digital communication
device 12 at the
subscriber's premise for an outgoing call or in response to receipt by digital
communication device
2 5 12 of a call SETUP message for an incoming call ti-om a Telco ISDN switch.
Execution proceeds
to block 510 where the processor 30 checks whether the tirst call has been
established. Block 510
represents conventional handshaking as described above with regard to block I
10 of Fig. 5. If the
call is not established, the NO branch is taken ti~om block 51 () to block 515
where the call is rejected
BOC9-1994-0024CA5 2 ~
CA 02412725 2002-12-19
and a busy signal is returned to the communication device 12. Next, the
processor 30 returns to the
IDLE block 500.
Referring back to block 510, if a call is established the YES branch is taken
from block 510
to block 520 where the first call is connected to a first B-channel. Execution
proceeds to block 525
where a check is made to determine whether a DISCONNECT call request has been
made, and if
it has, the YES branch is taken from decision block 525 to block 530 to end
the call and release the
B-channel. The system will then return to the idly state at block 500. If no
disconnect request is
made, execution proceeds from block 525 to block 535 where a check is made to
determine whether
a request has been made from another digital device 12 on the same multi-drop
S-bus 22 to share the
communication session with the first digital device; 12. The second digital
device 12 could be for
example, another phone, a fax, etc. If the second digital device 12 has not
made a share request, the
NO branch is taken from block 535 back to Mock 525. Thus, it can be seen that
when one call is
active the system will remain in a loop between blocks 525 and 535 while
waiting for either a share
request from a second digital device 12 or a request from either end of the
first call to disconnect the
first call.
Referring back to block 535, if a share request is made, the YES branch is
taken to decision
block 540. At decision block 540 the processor 30 checks whether the second B-
channel is available.
If the second B-channel is busy, then the 1' ES branch is taken from decision
block 540 to block 545
where the call is rejected, a busy signal is returned to the second digital
device 12 and the system
2 0 returns to decision block 525.
Referring back to block 540, if the second B-channel is available then the NO
branch is taken
from block 540 to block 550 where the second digital device 12 is connected to
the second B-
channel. In the next two blocks 555 and 560 the processor 350 will mix the
voice signal of one of
the B-channels with the voice signal of the other B-channel so that each of
the three parties can listen
2 5 to each other. The voice mixing of the two B-channels in blocks 435 and
440 is identical to the voice
mixing described above with regard to blucks 350 and 355 of Fig. 8. This voice
mixing of the two
B-channels by the processor 30 will continue until one of the calls is
disconnected from the call as
shown by blocks 555, 560 and 565. When a request is made from any
communication device on the
call to disconnect its respective call, the ~'E:S branch is taken from
decision block 565 to block 570
BOC9-I 994-0024CA5 22
CA 02412725 2002-12-19
where the corresponding B-channel is released by the processor 30. Execution
then proceeds to
block 535 where execution proceeds as described above.
Any one or more of the call processing programs can be included in network
adapter 10
depending on the class services that the subscriber desires to have. In
addition, it should be
understood that although each of the call processing programs except Fig. 9
were described with
regard to analog devices 6, the methods of the present invention can also be
performed with adapter
using digital devices 12. In addition. the adapter 10 can be used with analog
devices of a
subscriber that only has an analog class of service or digital devices of a
subscriber that only has
a digital class of service.
10 In another embodiment of the present invention, special flash hook and
touch tone commands
allow a user to perform call hold/rctrieve, call waiting and three way call
conferencing functions
when the communication device 6 is an analog telephone coupled to the ISDN
network via the
adapter 10. In addition, if the user subscribes to multiple call appearances
provided by the telco,
then up to a six way conference call can be established on the analog phone.
Each of these functions
can be performed on one B-channel using the analog phone when a user has
subscribed to EKTS
service on the ISDN network. The analog signals (switch hook and touch tone
commands described
below) input by a user to the analog phone are converted to ISDN EKTS signals
using the interface
circuit 39, DTMF decoder 41 and the tiltcr 4.s shown in Fig. 4 as described
above.
A typical telephone handset for an analog phone includes a switch hook and 12
buttons
(digits 0-9, * and #). There are three types of hook dashes that can be used
by the handset in
accordance with the present invention. A short hook Clash is a temporary
depression of the switch
hook that lasts less than one second. Some handsets have a "Clash" key which
can be used to
generate a short hook dash. A long hook flash comprises a temporary depression
of the switch hook
for longer than two seconds. A long hook Clash is treated as if the phone was
placed on-hook for a
2 5 prolonged period of time and then taken off=hook. A dash key should not be
used to generate a long
hook flash. The third type ofswitch hook activity is a double he>ok flash
which comprises two short
hook flashes, back to back within a two second period.
By utilizing these switch hook activities a user can place a call on hold
while answering a
waiting call, place a call on hold and dial another call and retrieve a call
placed on hold. In addition,
BOC9-1994-0024CA5 2;
CA 02412725 2002-12-19
if multiple call appearances have been subscribed to, the user can place two
calls on hold and dial
a third call and retrieve a call placed on hold in order of the oldest call on
hold to the newest.
Referring to Fig. 1 l, there is shown a state table listing the various states
that a user can be
in along with the state resulting from one of the three dash hook commands. If
there are no calls
waiting, no calls on hold, no conference call and the user hears a dial tone,
busy tone or error tone
the result of any of the three dash hook activities will be a dial tone.
A short hook flash is used to hold active calls and/or connect to non-active
calls. If a user is
engaged in an active call, a short hook Clash will always place that active
call on hold. If there is no
call waiting, no calls on hold and no conterence anti additional call
appearances are available, the
0 user will be provided a dial tone. If no additional call appearances are
available, the user will hear
an error tone. If there is a call waiting and no conference, the user will be
connected with the waiting
call. If there is no conference, but there is a prior call on hold, the user
will be connected with the
oldest call on hold. When the current state is a dial tone and their is one
call on hold, a short hook
flash will connect the user to the call on hold. If there are two calls on
hold and a dial tone, the user
will be connected to the oldest call on hold.
The result of a double hook flash will always be a dial tone if sufficient
call appearances are
available. If sufficient call appearances are not available, the result of a
double hook flash will
always be an error tone. The active call at the time of a double hook flash
will be placed on hold if
no conference call has been established. Any waiting calls at the time of the
double hook flash will
2 0 also be placed on hold. Calls that were already on hold at the time of the
double hook flash will
remain on hold. When the current state is a dial tone and their is one or two
calls on hold, a double
hook flash will keep the user in the current state.
If there is currently an active call and no conference, the result of a long
hook flash will
always be to disconnect (hang up) the active call. If there wire no calls
waiting or on hold at the
time of the long hook flash, a dial tone will be presented. If there was a
call waiting at the time of
the long hook flash, the user will be connected to the waiting call. If there
was no call waiting, but
there were calls on hold, the user will be connected with the oldest call on
hold. When the current
state is a dial tone and their is one call on hold, a long hook dash will
connect the user to the call on
BOC9-1994-0024CA5 2~
CA 02412725 2002-12-19
hold. If their are two calls on hold and a dial tone the user will be
connected to the oldest call on
hold.
While there are waiting calls, or calls on hold, the user may go permanently
on hook. If the
user does so, the user's phone will ring back and when he answers the phone,
he will be connected
with the same party as if he had done a long hook flash. The various states
for the switch hook
activities described above are summarized in rows 1-6 of the state table shown
in Fig. 1 1.
In another embodiment of the present invention, the three switch hook
activities along with
a touch tone command can be used to produce up to a six way conference call on
the analog phone
coupled to the ISDN network via network adapter l0. The conference call can be
handled on one
B-channel according to EKTS standard,. First it should be noted that in order
to produce a
conference call, the user must subscribe to either the ISDN 3 WAY CONFERENCE
facility or the
ISDN 6 WAY CONFERENCE facility provided by the telco. If a user attempts to
set up a
conference call and he has not subscribed to either c>f these facilities, he
will receive an error signal.
The two calls that he was attempting to conference will both be left on hold.
If a user attempts to
add a call to an existing conference and insufficient conference slots are
available he will receive an
error signal and the last call will be terminated. The conference will
continue to be on hold. It should
further be noted that while a conference is established, all incoming calls
are returned as busy.
Management of incoming calls is not required while a ec>nf'erence is active.
In order to establish a conference call, a user places a call to a first party
and establishes an
2 0 active call. Next, the user performs a short hook flash (or a double hook
flash) which will place the
active call on hold and gives a dial tone (see row 2 of Fig. 1 I ). The user
then places a second call
and waits for an answer. Once con~~ected to the second call a double hook
flash will place the
second call on hold and give the user a dial tone. (row 4). A three way
conference call can now be
established between the three parties by entering the command * * 1. There are
other methods of
2 5 getting to the point where a user will have two calls on hold and a dial
tone (see for example, row
3). A three way conference call can be established at any time there are two
calls on hold and a dial
tone by the command * * 1. It should be understood that * * I is exemplary
only and any three
characters can be programmed by one skilled in the art to perform the
functions of this command.
BOC9-1994-0024CA5 2>
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A user can place the conference on hold and make an additional call. This is
done by
performing a short hook Clash (or a doable hook dash) while in conference.
This will put the
conference on hold and produce a dial tone. The non conference call can then
be placed. The non
conference call can be terminated by performing a long hook flash. This will
cause the user to rejoin
the conference and to tet-tninate the non conference call. If the user
received a busy signal from the
non conference call the user can return to the conference by performing a
short or a long hook flash.
Up to three additional parties can be added to the conference call as long as
the user has
subscribed to the ISDN 6 way conterence facility. To add a party to a
conference call, the conference
is placed on hold and a dial tone is generated by performing a short hook
flash while in conference.
Next, the new party is dialled and after the new party's phone began ringing
or the new party has
answered, the new party may be added to the conference by doing a second short
hook flash (or
double hook flash). (Note that if the new party joined the conference while
his phone was ringing
all parties to the conference will hear the ringing and as soon as the new
party answers the phone he
will join the conference.) This will add the new party to the conference as
well as return the user to
the conference. These steps can be repeated to add up to three additional
parties for a six way
conference call. If the user did not wish to add the new party to the
conference, then instead of
performing the second short hook flash the user can perform a long hook flash
which will terminate
the call made to the new party and return the user zo the conference as
indicated above.
The last party that was added to a conference call can be dropped by a
entering a drop
2 0 command. A situation where a user may want to drop the last party may
arise where the call was
added to the conference while it was ringing and the called party never
answered or the answering
party was not the person targeted by the call or was unavailable. The last
call added a three way
conference call established.
After the conference call is established, the conference continues to exist as
long as there are
2 5 at least two potential participants. That is, if distant parties who were
in a conference have hung up
to the point that only the user and one distant party are left, this is still
a conference call. A
conference call can be ended in one of two ways. A conference call may be
terminated if all distant
parties hang up their respective phones. It can also be ended if the user
performs either a long hook
flash while a part of the conference or peunanently goes on hook while the
user is part of the
BOC9-1994-0024CA5 2~
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conference. A long hook flash performed while the conference exists but while
the user hears a dial
tone would only cause the user to rejoin the conference.
While the invention hats been particularly shown and described with respect to
preferred
embodiments thereof; it should be understood by those skilled in the art that
the foregoing and other
changes in form and detail may be made therein without departing from the
spirit and scope otthe
invention as detined in the appended claims.
BOC9-1994-0024CA5 27
