Note: Descriptions are shown in the official language in which they were submitted.
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METHODS FOR PERFORMING INTELLIGENT NETWORK SERVICES
WITH AN ISDN NETWORK TERMINATOR LOCATED AT
A SUBSCRIBER'S PREMISE
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates generally 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
i 5 voice, data, facsimile, and video. 'There are tevo 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
requires less overhead than providing a discrete acce:,s line for each
service, and results in a total
lower cost of service.
An ISDN Basic Rate Interface (BRI) consists of three channels, referred to as
two B channels
plus a D channel (2B + D), in which all signals tlowin~; over the external
telephone company (teleo)
lines are carried in a baseband digital form and in a standardized frame
format. With this
2 5 arrangement, the B channels are the basic user channels which carry
digntal voice, high-speed data,
and other functions at a maximum channel rate of G4kbps. The D channel bit
rate in this interface
is I6 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 Interface consists of multiple
B channels and one
64 kbps D channel having primary rates of either 1544 kbps (23B -+- D) or 2048
kbps (30B + 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, ur 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 ur 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 telcu 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 in order to offer 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 fixed, but internal POTS wiring is
either bypassed or
2 0 elaborately modified in order to provide a curnmunication path for digital
ISDN signals if only one
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 of service. 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 terminal equipment, which had et~ectively
become useless, in order
to maintain a single (digital) class of service. The desirable solution is
disclosed in earlier filed
United States Patent Number. 5,448,635, tiled June 30, 1993 and owned in
common with this
invention. This application discloses an architecture and apparatus for
connecting both analog and
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digital devices in a subscriber premise to a single subscription line in an
1SDN 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 ID) which are currently handled by the
central oft3ce switching
system and require the user to pay additional charges for their use. An 1SDN
network includes an
ISDN central office switching system which is connected to communication
devioe(s) 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 and 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 off ce switching system by transmitting call handling
messages (e.g., SETUP,
ALERTING, CONNECT, DISCONNECT) hrom 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 currently require processing bythe 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 1 characteristics of ISDN user-
network interfaces (CCITT
2 0 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 h<is 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 telcphoncs currently operate with EKTS
and call appearance call
handling (CACH) EKTS standards provided by the 1SDN network. The digital EKTS
phones have
numerous buttons and display lights (or a digital display) to allow a user to
perform 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. However, there is no such EK'T'S
facilities used for analog
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telephones. In addition, since the netw<:>rk 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 conferencing and call hold/retrieve
on an analog telephone
coupled to ISDN EKTS service.
Accordingly, it is an object of tlae present invention to provide a
subscriber's premise with
a network terminator based arrangement which can utilize the I3-channels of an
ISDN network to
perform call waiting, caller identitication, 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 andior
analog devices at the
subscriber's premise. It is yet a further object of the present invention to
provide a user interface for
mapping actions performed on an analog telephone into EKTS signals recognized
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 te~nninator (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
network adapter includes a processor which can perform digital signal
processing functions in
accordance with the present invention. 'fhe adapter is operatively coupled to
the digital network and
a communication device at the subscriber's premise.
One embodiment of the present im ention 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 call an a communication device at the subscriber's
premise on a first
communication channel. Next, in response to a determination that a second call
is being made to the
subscriber's premise, the adapter will connect the second call on a second
communication channel.
Ifthe subscriber's premise does not include a second communication 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 there at the
user's option, the
adapter eliminates the need for intervention tr~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 ti-om the call SETUP message.
Next, the processor within
the adapter will voice synthesize the first message to tine 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 voice
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 informtnion (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. fhe 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 tiom the communication
device a call setup
request to establish a second call. Atter 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 first 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
voice 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 Bl. This
automatically establishes a three way e<onfereuce 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 will initiate a first connection
on a first communication
channel between the first communication device and a second cot7~munication
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 first 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 destinati~,m. The processor will
continue voice mixing
until a disconnect request is made tcom 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 ofthe above described embodiments the digital network can be an
lntel,~rated 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 ofthe present invention, flash hook and touch tone
commands allow
a user to perform call hold/retrieve, call waiting and three way call
conferencing functions on an
analog telephone coupled to an ISDN network via the network terminator of the
present invention.
In addition, if multiple call appearances are provided by the telco, then up
to a six way conference
call can be established with tine analog phone. Each of these call
conferencing functions are
performed on one B-channel according to EKTS 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 ofthe present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. I 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 diagram 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 diagram 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.
2 5 Fig. 6 is a partial flow chart of an altec-nativ a embodiment of the call
processing program of
Fig. 5.
Fig. 7 is a flow chart of a call processing prograim used ter caller
identification in the adapter
based implementation of Fig. 2.
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Fig. 8 is a flow chart of a call processing program used for call conferencing
in the adapter
based implementation of Fig. 2.
Fig. 9 is a flow chart of a call processing program used for call forwarding
in the adapter
based implementation of Fig. 2.
Fig. 10 is <~ 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. I I 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
I 0 of three flash 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 l; nited States Patent
No. 5,448,635, filed June 30,
1993 and owned in common with this invention.
The wiring in a subscriber premise comprises tour signal wires. These wires
extend to a
junction box 2 that connects the customer premise to an ISDN cattier 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-Yellow pair of wires 26
is coupled to the ISDN
digital carnet network. Telco carrier network wiring at the junction box 2 is
connected to the pair
of wires 26 and isolated from the pair of wires 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 fore, and
an S-bus 22 through which digital devices 1? (e.g., digital telephone
equipment, fax machine, etc.)
are connected. The digital and analog interface network adapter l0 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 tc»nterface with the
Telco ISDN
carrier network. Likewise, the G-R wires are "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. 1, 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 wii°ing 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 arrangement, signals tlowing 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 foam between
the adapter 10 and the
2 5 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 forth between the
device and the adapter 10 via the S-bus 22; get converted in the adapter I 0
between four wire S-bus
digital form and two wire digital ISDN; and pass in the latter forth between
the adapter 10 and the
external earner 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 analcog device to
the junction box 2
(configuration not shown).
Referring now to Fig. 2, number I 0 refers to the block diagram of the digital
and analog
network adapter architecture constructed according to l:he 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 8031 which is cold by INTEL. Alternatively, the
processor 30 can be
a Digital Signal Processor (DSP) which also performs microprocessing
functions. One suitable DSP
is the MWAVE MSP1.0 which is sold by IBM. ~~ suitable U interface device 36 is
the PEB 2091;
a suitable ISDN access controller 40 is the PEB 2070 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 interconneca 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 4!), bus 48 may also be used to
connect other diverse
voice/data modules (sources cor targets for the D charnel, 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 anatlog devices
within the subscriber
premise. The pair of wires 26 may be the B-Y pair, according to the typical
POTS configuration, as
descri bed.
Thus, a signal coming from the'Telco 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 loop.
The ECH method and
resultant TTL level binary stream are in contunnance with ANSI standard
T1.601.
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 0 10 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. T'he U interface 36 is of the
type to accommodate
a 2B I Q, or other standard digital channelized form as 'required by the local
telephone network. For
2B 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 characterised 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 80Khz 2B 1 Q two
wire subscriber loop
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signal at the U interface 36 may be converted into two discrete l60 Khz
sitmals (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 ti>ur wire transtbnner that
supports up to eight
digital devices according to the ANSI T1.605 standard.
The telephone interface 38 is 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 f-or 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 codec filter 43 under control of 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-55048 sold by Harris
Corporation; a suitable DTMF detector 41 is the MC 145436 sold by Motorola; a
suitable audio
ringing codee filter is the PSB 2160 sold by Siemens Components, Inc.
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 tlovr.Ting between any analog device
and the external ISDN
network pass in analog form through the analog hybrid 64 and telephone
interface 38; get converted
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in the telephone interface 38 between analog and two wire digital ISDN forms
such as EKTS; and
pass in the latter form to the ISDN 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, ?6 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 au
of the present invention
that the processor 30 will perform power on diagnostics ands 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 of the call
processing proln-ams
described below are stored in EPROM 46 and Ioade<l 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
i 5 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 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
2 0 enters the IDLE state indicated at block l On. As shown in block 105,
program execution begins
either in response to a call SETL~ P 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 ti-om a'felco ISDN switch. Execution proceeds to
block 110 where
the processor 30 checks whether the first call has been established. Block 110
represents
25 conventional handshaking whereby the communication device 6 and the ISDN
switch are
exchangring call handling messages such as SETUP ACK, ALERTING, CONNECT, etc.
During
block 110, if the call is not established (e.g., a busy line), the NO branch
is taken from block 1 10 to
block 1 15 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 l OC~.
BOC9-1994-00?4CA3 t 3
CA 02412768 2002-12-19
Referring back to block 110, when a call is established the YES branch is
taken form block
1 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 if it has, the
~'ES branch is taken from
decision block 125 to block 130 to end the call and release the B-channel. The
system will then
return to the idle state at block 100. 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 an incoming call while the; first
call is still active. If there
is no setup request for an incoming call, the MO branch is taken froth 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 for either an incoming call setup request or a request
to disconnect the first
call.
Referring back to block 135, if a call S ETUP message is received by
communication device
6 for an incoming call, the YES branch is taken li-om block 1 3S 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, a busy 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 12_5 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 j will be concocted 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 fi. The subscriber will then have an option
to receive/not receive
the second call by toggling%not 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
160 to block 165 where the subscriber's communication device 6 will be
connected to the second B-
channel by processor 30 to allow the subscriber to communicate with the second
caller. Execution
then proceeds to decision block 170.
BOC9-1994-0024CA3 t a
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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. 1f a disconnect is requested fmm either party to the first
or second call, the YES
branch is taken from block 170 to block 1?5 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 ti~om 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 ~'ES branch is taken from block 180 to block
18~ 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 ofthe BRI 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
18(.) to block 160 and continue as described above. Thi: logic resulting from
blocks 160, 165, 170,
180 and 185 allows the subscriber to toggle indefinitely between the first and
second calls until a
disconnect message is made from either end of the first or second calls
(subscriber included).
Referring to Fig. 6, there is shown an alternative embodiment of the call
waiting program 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 embodiment, the subscriber has a first
communication device
2 0 connected to the t3rst 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
from 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 off hook). If the subscriber chooses not to
accept the call, the NO
branch is taken from block 154 to block 12s 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
BOC9-1994-0024CA3 ~ 5
CA 02412768 2002-12-19
made to determine whether a disconnect request is made by any of the patrties
to disconnect one of
the calls. If a disconnect is requested ti-om either party to the first or
second call, the YES branch
is taken from block 156 to block 158 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 ti-om block
I 56 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 ~'ES
branch is taken from
block 162 to block l64 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 SE'TU P mcssagc was not
received, execution will
proceed directly from block 162 to block 156 and continue as described above.
By connecting the two calls on the two B-channels of a BRI and allowing the
subscriber to
accept (toggle between calls when only one device is coupled to the BRl 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 perfbrn call waiting at the
subscriber's premise.
Referring now to Fig. 7, there is illustrated a flow chart including the basic
process steps used
by processor 30 in executing a call processing program which implements caller
identification 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 20(a. Program execution begins in
response to receipt by
communication device 6 of a call SETUP message far 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 l0 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
BOC9-1994-0024CA3
CA 02412768 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 block 225. the prof,~-am 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.
After 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 from the SETUP
message received
from the ISDN switch. Execution then proceeds to block 235 whore the number is
compared to
numbers in a preprogrammed look up table (LUT). The LUT 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
from block 235 to block 245 where the additional information (e.g., name)
which corresponds to the
number in the LUT is voice synthesized to the receiver. Execution proceeds ti-
om block 240 or 245
1 S 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 request is made and the
processor 30 connects the call
to the available B-channel as shown at block 255. Execution proceeds ti-om
block 255 to block 260
2 0 where the processor 30 will remain until a DIS(~ONNECT call request has
been made from either
party to the call. Once a disconnect message is received, the Y'ES branch is
taken from decision
block 260 to block 265 to end the call and release the I3-channel. The system
will then return to the
idle state at block 200.
Referring back to block 250, i f a connect request is not made, the program
proceeds to block
2 5 270 where the processor 350 checks whether the subscriber chuse not to
receive the call. If no
choice is made at that bane, ~xecutior~ 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
BOC9-1994-0024CA3
CA 02412768 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 cm the recc;ive;r, e.g., a short
hook flash to accept or a
long hook flash to reject the call.
Referring now to Fig. 8, there is illustrated 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, pro~,»-am
execution begins
either in response to a call SETUI' message initiated by connnunication device
6 at the subscriber's
premise for an outgoing call or in respunse to receipt by communication device
6 of a call SETUP
message for an incoming call from a rt"elco ISDN switch. Executicm proceeds to
block 3I0 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'_VO branch is taken from block 3 l0 to
block 315 where the call is
rejected and a busy signal is returned to the cc»nmunication de~~ice Ci. Next,
the processor 30 returns
to the IDLE block 300.
Referring back to block 310, ifa call is established the YES branch is taken
from 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 DISC'ONNEC'T call request has
been made from
either party, and if it has, the YES 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- I 994-0024CA3
CA 02412768 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 :>0 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 3~0 and 35~ the processor 30 will mix the voice sigmal
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 ofone B-
channel (B 1) is copied
downstream of B1 to the upstream of the other B-channel (B2) while in block
355 the local voice
data signal of B2 is copied downstream of B2 to the upstream i>f B 1. This
voice mixing can be
summarized by the following equations:
L1S(B) = US(B 1 ) + US(B2)
DS(B 1 ) _- US(B2) t DS(B)
DS(B2) = US(B1 ) + DS(B)
where US is upstream and DS is downstream. The voice mixing can be performed
utilizing
conventional digital sigmal 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 ti-om 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 365 where the corresponding B-channel is
released by the
processor 30. Execution then proceeds to block 325 where execution proceeds as
described above.
This method can be used to establish up to three calls on the conference call.
By connecting each
ofthe 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 t.o conference 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
BOC9-1994-0024CA3 t9
CA 02412768 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 400. Program execution begins in
response to receipt by
communication device 6 of a call SETUP message for an incoming call ti-om the
ISDN switch as
shown 405. Execution proceeds to block 4l () 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 tbrwarded. 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., AL.ER'rING, CONNECT, etc.
Execution proceeds from block 410 to decision block 41 S where the processor
30 checks
whether the connection has been established between the subscriber's terninal
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 ti-om block 41 S 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.
Referring back to block 415, if the connection is established on the first B-
channel, the YES
branch is taken from block 41 S to block 42S where the incoming call made to
the communication
device 6 is accepted. Next, execution proceeds 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 fi 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 43S and 440 where the processor 30 will mix the
voice signal
2 5 of the first B-channel (B 1 ) 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 43S and 440 is identical to the voice mixing
described above with
regard to blocks 350 and 3SS of Fig. 8. By establishing the tirst and second
connections described
BOC9-1994-0024CA3 20
CA 02412768 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 for the Telco switch to ti~rward the
call.
Execution proceeds from block 440 to block 44S where the processor 30 checks
whether a
disconnect request is made ti-om either party to the call. if a request is
made to disconnect the
forwarded call form either end, the YES branch of block 44S is taken to block
4S0 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 4SS.
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 block 460. If a new call setup request has
not been made,
execution proceeds to blocks 43S and 440 where data mixing continues. If a new
call setup request
is made, then the YES branch is taken from Mock 460 to block 46S where the new
call is rejected
and a busy signal is returned to the new calling party. Execution then
proceeds to blocks 43S and 440
as described above. Thus, the processor 30 will loop within blocks 435, 440,
445, 460 and 46S 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 ti~rwarded location.
Referring now to Fig. 10, there is illustrated a flow chart including the
basic process steps
used by processor 30 in executing a call processing program which allows two
digital
communication devices 8 on the same S-bus '?2 to share a communication
session. Again, the coding
of the process steps of this flow chart into the instructions suitable to
control the processor 30 will
2 0 be understandable to one having ordinary skill in the art of programming.
After performing initial program load and power cm diagnostic routines, the
processor 30
enters the IDLE state indicated at block S0t>. 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 inccnnir~g call ti-om a Telco ISDN
switch. Execution proceeds
to block S 10 where the processor 30 checks whether the first call has been
established. Block 510
represents conventional handshaking as described above with regard to block 1
I 0 of Fig. S. If the
call is not established, the NO branch is taken ti-om block S 10 to block S 1
S where the call is rejected
BOC9-1994-0024CA3 2 t
CA 02412768 2002-12-19
and a busy signal is returned to the communication device l2. Next, the
processor 30 returns to the
IDLE block 500.
Referring back to block S 10, if a call is established the YES branch is taken
from block 510
to block 520 where the first call is connected tc> a first B-channel.
Execution proceeds to block S25
where a check is made to determine whether a DIS(~ONNEC'T call request has
been made, and if
it has, the YES branch is taken from decision block S2S to block S30 to end
the call and release the
B-channel. The system will then return to the idle state at block 500. If no
disconnect request is
made, execution proceeds from block S25 to block S3S where a check is made to
determine whether
a request has been made from another digital device l 2 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 S3S back to block 525. Thus, it can be seen that
when one call is
active the system will remain in a loop between blocks 52S and S3S 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 S40 the processor 30 checks whether the second B-
channel is available.
If the second B-channel is busy, then the YE S branch is taken ti-om decision
block S40 to block S4S
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 S2S.
Referring back to block 540, if the second B-channel is available then the NO
branch is taken
from block S40 to block S50 where the second digital device 12 is connected to
the second B-
channel. In the next two blocks SSS and S6l) the processor 3S0 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 ofthe two B-channels in blocks 435 and 440
is identical to the voice
mixing described above with regard to blocks 3_50 and 3SS 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 SSS, S60 and S6S. When a request is made ti-om any
communication device on the
call to disconnect its respective call, the YES branch is taken from decision
block 565 to block S70
BOC9-1994-0024CA3 ?3
CA 02412768 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 suhscriber desires to have. In
addition, it should be
understood that although each of the call processing programs except Fig. 9
were desct~ibed with
regard to analog devices 6, the methods ofthe 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 ofthe present invention, special dash hook and touch
tone commands
allow a user to perform call hold/retricve, call waiting and three way call
conferencing functions
when the communication device (~ 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 cm 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 arc converted to ISDN EKTS signals
using the interface
circuit 39, DTMF decoder 4 t and the filter 43 shown in Fig. 4 as described
above.
A typical telephone handset for an analog phone includes a switch hook and 12
buttons
2 0 (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 flash is a temporary
depression of the switch
hook that lasts less than one second. Some handsets have a "flash" key which
can be used to
generate a short hook flash. A long hook flash ccnnpri;~es a temporary
depression of the switch hook
for longer than two seconds. A long hook flash is treated as if the phone was
placed on-hook for a
2 5 prolonged period of time and then taken oft=hook. A flash key should not
be used to generate a long
hook flash. The third type of switch hook activity is a double hook flash
which comprises two short
hook flashes, back to back within a rivo 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,
BOC9-1994-0024CA3 23
CA 02412768 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 cm
hold to the newest.
Referring to Fig. 1 1, 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 Clash 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 Clash hook activities will be a dial tOtle.
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 hash will always place that active
call on hold. If there is no
call waiting, no calls on hold and no conference and additional call
appearances are available, the
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 conterence, 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 Clash will always be a dial tone if sufficient
call appearances are
available. If sufficient call appearances are nut available, the result of a
double hook flash will
always be an error tone. The active call at the time of a double hoc>k 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
also be placed on hold. Calls that were already un 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 were no calls
waiting or on hold at the
2 5 time of the long hook Clash, 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 uldest call on
hold. When the current
state is a dial tone and their is one call on hold, a long hook flash will
connect the user to the call on
BOC9-1994-0024CA3 z~
CA 02412768 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, th.e user may go permanently
on hook. If the
user does so, the user's phone will ring back and when he answers the phc~nc,
he will be connected
with the same party as if he had done a long hook Clash. 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 10. The conference call can
be; handled on one
B-channel according to EKTS standards. 1=first it should be noted that in
order to produce a
conference call, the user must subscribe to either the 1SDN 3 WAY CONFERENC.'E
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 of 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 conference 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 for a double hook
Clash) which will place the
active call on hold and gives a dial tone (see row 2 of Fig. 1 1 ). The user
then places a second call
and waits for an answer. Once connected to the second call a double hook Clash
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 * * 1 is exemplary
only and any three
characters can be programmed by one skilled in the art to perforn the
functions of this command.
BOC9-1994-0024CA3 25
CA 02412768 2002-12-19
A user can place the conference on hold and make an additional call. This is
done by
performing a short hook flash (or a double hook flash) 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 performin:,; a long hook flash. 'This
will cause the user to rejoin
the conference and to terminate 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 conference feel lity. 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 Clash (;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 perterm a long hook flash
which will terminate
the call made to the new party and return the user to 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 Iett, this is still
a conference call. A
conference call can be ended in one oftwo 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 permanently goes on hook while the
user is part of the
BOC9-1994-0024CA3 2~
CA 02412768 2002-12-19
cont~rence. 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 has 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 tcom the
spirit and scope of the
invention as defined in the appended claims.
BOC9-1994-0024CA3 27
