Note: Descriptions are shown in the official language in which they were submitted.
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APPA~U~llUS A~D ~ ~-~v IN SUPPORT OF CO~IPLETING
'rwo CAI-LS USING ~ OG INl'ERFACE TO TEL~.~m~h~ h t~ k.
Bachy o~ud of the In~ention
The present invention relates to an apparatus and
method for completing at least two calls to or from a
premises that is connected by a single point-of-
attachment (or telephone line) to a telephone networkand more particularly to an apparatus and method that
processes multiple calls at the premises.
Multiple calls often are established over digital
networks from terminals connected by a point-of-
attachment identified by a single terminal number. Forexample, networks using packet-switched data networks,
described in ITU-T reco~n~tions X.25, use digital
terminations and allow multiple calls over the network.
Other examples include frame-relay networks, described
in ITU-T recommen~ation I.233; narrow-band ISDN,
described in ITU-T reComm~n~tion I.210; and broad-band
ISDN networks, described in ITU-T reco~n~tion I.211.
These services use digital terminations that can be
expensive to implement and maintain.
" 20 It would be advantageous if a premises connected by
a point-of-attachment to the Public Switched Telephone
Network (PSTN) with the standard, analog "tip-and-ring"
interface could carry a modulated signal between the
premises and the PSTN that includes multi-call
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capability from terminal equipment located on the
premises, such as a telephone, video, fax machine, or
personal computer. This would be advantageous, for
example, if someone at a premises is using a fax machine
while at the same time a telephone call needs to be made
to a different location. Other examples could include
someone making two telephone calls to the network, or
using a computer and fax machine or a telephone and
personal computer simultaneously.
It is therefore desirable if a method and apparatus
could combine, at a premises, at least two calls to
different locations originating from terminal equipment
located at that premises, where the apparatus connects
the combined calls to a public switched telephone
network by a point-of-attachment without digital
termination such as ISDN systems.
Sl ~y of the Inv~ntion
The present invention provides a method and
apparatus for combining, at a premises, at least two
calls originating from terminal equipment located at
that premises and connecting the combined calls to a
public switched telephone network by a point-of-
attachment where one dial tone is provided on an analog
interface to the premises. In typical realizations of
the present invention, the point of attachment has a
single telephone number associated therewith. The
method and apparatus of this invention permits multiple
calls, such as an analog phone, video, data, fax and
comparable calls over a single analog interface. It can
be extended to allow an increased number of calls by
utilizing additional analog interfaces. Such an
extension, sometimes known as a multi-link arrangement,
provides for any allocation of the multiple calls across
the plurality of analog interfaces.
In accordance with one aspect of the present
invention, a control channel is established between the
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telephone network, such as a public switched telephone
network, and the terminal e~uipment located at the
premises. At least two calls originating from premises
equipment and the control channel are combined at the
premises into a modulated analog signal having a
separate ch~nne1 for each call. Likewise, any incoming
calls are combined with the above calls and with the
control channel ~or transmission between the customer
premises and the public switched telephone network.
Identity in~ormation is transmitted ~rom the originating
terminal equipment through the control channel to aid in
determining a remote de~rice with which a call i5 to be
~ssociated. This includes auxiliary in~ormation ~or
progressing the call. The signal is transmitted ~rom a
modulation/demodulation device as a modulated analog
signal to the public swi~ched te7ephone network. The
modulated analog signal is split into the respective
calls and the control ch~nnel. The calls are then
forwarded to a respective remote device based on
identity in~ormation and auxiliary in~ormation received
through the control channel.
In one aspect of the present invention, the calls
can be split at the public switched telephone network.
The public switched telephone network can also include a
cellular network. Identifiers are associated with each
channel for dis~inguishing each ~h~nn~ within the
public switched telephone network. Each ch~nn~1 can
also comprise a plurality of information blocks, and
identifiers can be associated between the public
switched telephone network and the terminal eguipment
~or each ch~nn~l to distinguish the information blocks
belonging to each call or control ch~nnel.
In addition, in accordance with the present
invention the premises apparatus that combines the calls
also splits the calls to return information to the
respective terminal equipment at the premises.
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Brief Description of the Drawings
FIG. l is a simplified block diagram of a telephone
network including intelligent network components of a
pu~lic switched telephone network and other components
S suitable for use with the present invention.
FIG. 2 is a simplified block diagram of a multi-
call terminal apparatus in accordance with an embodiment
of the present invention.
FIG. 3 is a more detailed block diagram of the
multi-call terminal according to an embodiment of the
present invention.
FIG. 4 is a schematic representation of a control
channel between terminal equipment at the premises and
the public switched telephone network.
FIG. 5 shows in greater detail multiple c~nn~ls
between terminal equipment and the public switched
telephone network and respective calls extending to
remote units.
FIG. 6 shows in greater detail the use of the
identifiers for information blocks to distinguish
be~ween calls.
FIG. 7 is a schematic diagram showing operation of
the control ~h~nnel~
FIG. 8 is a block diagram showing one aspect of the
method of the present invention.
Detail~d Description
Referring now to FIG. 1, there is illustrated an
overview of the pu~lic switched telephone network 10
that is connected via a ~irst Local ~ch~n~e Company
(LEC) 12 to a premises 14, such as a residential
premises, having a fax machine 16 and an analog
telephone 18. ~he present method and system allows
multi-call capability to and from the premises 14
connected via an analog interface having a single phone
number. Multi-call capability in accordance with the
present invention includes the merging o~ two or more
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outgoing calls such as analog phone, data, video, fax
and other similar calls and the separating of two or
more incoming calls. In accordance with the present
invention, the analog telephone 18 and fax machine 16,
as well as any other equipment ~not shown) such as
personal computer or video, are devices connected to or
included as part of multi-call terminal equipment 20
(hereafter Uterminal eguipment~), and includes a multi-
call interface apparatus 22 that includes a
modulation/demodulation device. The multi-call terminal
equipment 20 can be integrated into one physical
structure or box at the premises and can be located in a
small business, residential premises, or other premises
where a single point-of-attachment having a single phone
1~ line to a public switch telephone network uses an analog
interface. The modulation/demodulation device can be a
regular modem, limited distance modem, or a line driver.
Further detai~s regarding the multi-call interface
apparatus will be provided below.
The LEC 12 is connected to the premises 14 and
terminal eguipment 20 by a point-of-attachment having a
single phone line using an analog interface that
supplies one dial tone to the premises. In this example
of a public switched telephone network, 10, the network
includes Service Switching Points (SSP) 24 and a
standard CCS7 signaling network 26 that is connected to
a Service Control Point (S~P) 28, which also includes a
database 30 as is conventional. The PSTN 10 may also
include a cellular network 32 that is connected to a
Service Switching Point 24 via a Mobile Switching Office
(MSO) 34. Naturally, the present invention can be
implemented in other network configurations as well as
be understood from the description of the interface
apparatus and a service element that follows.
For purposes of describing the present invention as
shown in FIG. 1, the PSTN 10 also connects to a second
LEC 40, which connects to a second premises 42 having
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remote devices, e.g., fax machine 44 and an analog
telephone 46, and a third premises 48 having an analog
telephone 50.
A multi-call service element (MC-SE) 52 in the form
of an adjunct processor 54 is connected to the LEC 12
and i5 shown in this example, outside the network 10 and
in such a circumstance could ~e located in a separate
premises. Alternatively, MC-SE 52 could be an integral
part of the switch 24 or otherwise disposed to
communicate with SSP 24. MC-SE 52 includes processing
hardware, including a modulation/demodulation function
55, and may have an associated database 56 that could
store routing information, the telephone numbers of
those subscribers who use the present system and method
for establishing multi-call capability using a single
phone line and analog interface. The database 30 also
can be used for storing telephone numbers of
subscribers, and would be preferred. The ~EC 12
provides modem to modem connectivity between the first
premises and the MC-SE.
FIG. 2 illustrates a block diagram of an embodiment
of a multi-call interface apparatus disposed at the
premises 14 for interfacing the multiple sources of
calling information to the PSTN. In this figure the
interface device has three ports. A first port 210 is a
modem port that is coupled to the line providing access
to the network. Second and third ports 220 and 230 are
connected respectively to terminal equipment which seeks
to originate or receive calls from or to the premises.
As indicated above, such equipment can include an analog
telephone, a fax machine, a personal computer, video
devices or the like.
FIG. 3 illustrates in further detail an example of
the construct of the interface apparatus where one of
the equipment ports, 32, is coupled to a fax machine and
another, 33, is coupled to an analog telephone.
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The fax port 32 is an RJll port that has the
ability to do normal signaling ~hrough the port. An
artificial central office interface 301 is coupled to
port RJll and provides such central office ~unctionality
as collecting dialed dual-tone multi-frequency (DTMF)
signals and providing signals back to the fax machine
like "busy", "fast busy", "ringing", etc. Such an
interface can be conventional line port circuitry
including a 4 to 2 and 4 to 2 wire hybrid circuitry,
line circuit feed and off-hook detection capability.
The information from the fax machine (not shown) is then
treated by data handling elements 305 which include ~he
fax modem DAA 302, the Fax Modem CODEC 303 and a Local
Fax Modem 304. As a consequence, fax/data are supplied
to controller 310.
As for the port to which the telephone is
connected, 230 in FIG. 2, another RJll port connection
33 is provided. A second artificial central office
interface 331 of the type described above is coupled to
the RJll to provide the same types of functionality as
described above with respect to arti~icial central
o~ice inter~ace 301. -The telephone processing
circuitry includes an Audio CODEC 332 and an element for
providing audio compression 333 so that a voice signal
is transferred to controller 310. The audio codec can
be a conventional analog to ~-law PCM (A/D) and ~-law to
analog (D/A) conversion. The audio compression block is
a digital signal processor (DSP) implementing one of the
standards for speech compression such as AT~T's
internationals standards G.728 Low Delay CE~P Speech
Coding. In an optional configuration, equipment coupled
to the telephone port can include a speakerphone.
Additional elements which would be of assistance in
connection with such a configuration are shown as
speakerphone jack 33A and speaker phone Acoustic Echo
Canceller (AEC) 334.
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As can be seen, the fax/data information can ~e
provided from a fax machine coupled to RJll port 32
while at the same time voice information can be
transferred to the host from telephone equipment coupled
to RJ11 port 33.
The controller then acts as a call manager. The
controller multiplexes the information together thereb~
creating, in effect, two different communication
ch~nnels which are provided on or with a control channel
established to the public switch telephone networ~
interface. The multiplexed data from the controller 310
is then transferred to modem equipment 350 including
telephone line modem 351 and modem DAA 352. As a
consequence, the analog signal provided to the PSTN
interface includes the combined signals supplied by the
two independent communication devices, namely the fax
machine and the analog telephone.
It is also beneficial to assure that at least
telephone equipment will be able to access the PSTN
interface as a single e~uipment access if there is some
power failure. This is important for being able to
assure that emergency services, e.g., ~ type services,
are always available. FIG. 3 illustrates that a power
failure bypass mechanism 360 can be coupled between RJll
port 33 and the PSTN interface. Thus, where there is a
power failure the bypass mechanism would default to a
condition that bypasses the processing circuitry that
would otherwise transfer the telephone call to the
controller and instead directly connects the telephone
to the PSTN interface.
In accordance with this terminal equipment it i8
possible to combine the various independent sources of
information and transfer all of that information on the
same PSTN interface, such as a single telephone line
with a single assigned telephone number.
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The operation of this terminal equipment in
connection with the remainder of the network will now be
described.
~ eferring now to the flow chart of FIG. 8, and in
greater detail to FIGS. 4 through 7, details o~ the
method and system of the present invention are set forth
below with a description for completing multiple calls
from a residential premi~es having the equipment of FIG.
3 coupled to a fax machine 16 and an analog telephone
18. For purposes of clarity, each step corresponding to
a block begins with the numerical sequence starting at
loo. It should be understood that this description is
only one example. For purposes of de~cription, the
steps will be explained with reference to the MC-SE
positioned in the public switched telephone network.
The terminal equipment of the present invention
contacts the public switched telephone network, and more
particularly the multi-call service element and a
modulated signal is established (Block 100). It should
be understood, that the public switched telephone
network could contact the multi-call terminal equipment
for a first incoming call. The public switched
telephone network 10, through its multi-call service
element 52, then establishes a control channel 58 ~FIG.
4) for signaling purposes between the multi-call service
element and the terminal equipment 20 (Block 102). It
should be understood that the establishment of a control
channel could be done by either party after the modem
connection has been made regardless of which side
originated the modem connection. As shown in FIG. 4 the
control channel 58 is used for signaling and goes over
the modulated connection 60. The originating terminal
equipment 20 then can place a call, such as voice, data,
fax or video call, via the control ~h~nnel 58 and the
multi-call service element 52, to a remote multi-call
terminal element that is also a subscriber to the
present multi-call system, such as the fax machine 44
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shown in the second premises 42 in FIG. 1 and to a
remote existing terminal that is not a subscriber to the
present multi-call system, such as the analog telephone
50 shown in the third premises 48 in FIG. 1 (Block 103).
The multi-call service element 52, as part of the
public switched telephone network 10, then places a call
to the remote terminal equipment (Block 104). This is
done through an interface to a telephone switch by
signaling the need to set up a new call. The signaling
on this interface naturally depends on the relationship
between the multi-call service element 52 and the
telephone switch 24. For example, the relationship
could involve a mapping of the information flow
(messages) and the information elements (semantics and
syntax) between the Multi-Call interface apparatus/MC-SE
on the first interface and the MC-SE/telephone switch
interface. The mapping would involve mapping a connect
message on the first interface to an Initial Address
Message (IAM) on the second, providing, the MC-SE has
the capability of sending these messages to the SSP 24
as shown in FIG. 1.
When the call is made, a query is sent to the
database 56 contained in the multi-call service element
52 or database 30 to determine if the called number is a
subscriber to the multi-call system of the present
invention (Block 106). If the called number is not a
subscriber to the multi-call system, or if any remote
terminal equipment 42 is not using this service at the
time, a normal "tip-and-ring" call is placed to the
remote device (Block 108). During call set-up, unique
identifiers are associated with the call (Block 105) on
the calling side, and if the remote device is also a
subscriber to the present invention, at the called side
and the set of identifiers are associated with both
sides (110).
FIG. 7 shows the relationship of control channels
between MC-SE and Multi-Call Interface Apparatus when
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the called party is a subscriber to the multi-call
system. One control channel is designated by letter Ua"
between the premises and the PSTN, and ~bn between the
PTSN and the interface apparatus at the second premises
42. Both control channels are labeled with channel
identifier CId=0, (identi~iers). As illustrated, an
information channel is established from the first
premises interface apparatus into the PSTN, labeled
Cid=3, and a second information channel labeled CId=27
is established from PSTN 10 and the second premises MC-
TE 42. The network maintains a mapping of CId=3 and
CId=27 to support the call between premises 20 and
premises 42. If the called party was not a subscriber
channel identifiers would only be necessary on the path
from the calling party to the MC-SE 52.
When establishing a call using the control chAnnel
(after it has been setup), a unique identifier is chosen
by the establishing party (e.g., premises 14 for
outgoing call; MC-SE 52 for incoming call). This is
used subsequently by both parties to identify the
"blocks" or packe~s of informatlon that flow over the
channel (between the premises and the MC-SE) belonging
to each call associated with that premises. One packet
format that could be used with this inventor is
described in ITU-T Recnm~n~tion V.76 (1996),
incorporated herein by reference. The control ch~nn~l
has its own identifier (probably zero since it is the
first channel established). But these identifiers are
local to the premises/MC-SE interface. If the remote
end is also served by this invention, that second MC-
SE/premises combination picks its own identifier for the
channel serving that part of the call; if not, then a
regular call is set up and no identifier is used or
needed at the remote end. FIG. 6 illustrates a flow of
information blocks, having unique identifiers, between
the interface apparatus of the present invention and the
MC-SE of ~he present invention.
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In addition to the identifiers, auxiliary
information can be transmitted to aid in progressing the
call. Auxiliary information from the calling side could
include the type of calling device (e.g., fax) for
proper completion at the remote end or a request for
language translation between the two parties. For
incoming calls, auxiliary information includes the
remote side's calling party ID for display at the
premise, assuming it is not blocked.
The information blocks, or packets, carry
information pertaining to the control channel. For the
control channel, these can be messages for setting up
calls. For voice ch~nnels, these are compressed and
digitized voice packets. For fax ~h~nnels, these are
digital parts of the scanned page. The identifier is a
unique number or other unique identifier. Using the
unique identifier as established during the call set up,
the public switched telephone network 10, through its
multi-call service element 52, transmits information
blocks associated with that first call between the
multi-call terminal equipment 20 and the remote device
(Bloc~ 112).
In accordance with the embodiment shown in FIGS. 1
to 3, it is presumed that a first call from the premises
14 involves a fax machine 16 that desires to transmit
fax information to fax machine 44 at the second premises
42. That first call is established in accordance with
steps 100 to 112 of FIG. 8. Thus, the MC-SE 52
coordinates the transmission so that it is properly
routed from premises 14 to premises 42 over the
appropriately identified channels. Subsequently, and
during the ~irst call, the first premises may desire to
initiate a call to telephone 50 at the third premises
48. In that case the multi-call interface apparatus at
premises 14 creates the combined call signal combining
the fax call and voice call as described above with
respect to FIG. 3. The MC-SE receives the request to
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13
establish the second call (to telephone 503, splits the
combined signal and sends the respective portions fax
and voice, on to their intended destinations based on
identification in~ormation transmitted to the MC-SE with
the combined calls. The Flow Chart of FIG. 8, shows the
step of originating another call (or receiving another
'' call ), ~rom other terminal equipment in Block 114.
Furthermore, FIG. 5 illustrates, in schematic form the
in:Eormation t-h~nn~l configuration that exists after the
MC-SE 52 establishes both of the connections associated
with equipment 20.
When one of the calls is then finished (Block 116),
i~ there are any rem~;n~ng calls (~lock 118~, then
information blocks continue to be transmitted (Block
112) on the rem~; n;ng ch~nn.ols. If there are no
r~m~;n;~g calls, the connection can be terminated with
the public switched telephone network (Block 120).
The current invention as set forth in the apparatus
and method as described above now allows multi-call
capability even with the analog interface existing
between the public switched telephone network 10 and the
premises. Various advantages accrue as noted in the
following examples.
1) A telecommuter could be working at home and
accessing an e-mail server. While this interaction
occurs, the telecommuter also can place a voice call to
a fellow worker to discuss another project. The multi-
call service of the present invention provides the
capability of the telecommuter to originate two calls.
Additionally, the telecommuter could receive a call
while accessing the e-mail server.
2) A child can access a game server or "surf-the-
web". At the same time, the child's parents can
originate or receive voice calls.
3~ A worker in a "small-of~ice/home office" may
need to discuss an ongoing project with his/her partner
using material in a fax. The partner may not have the
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14
proper type of terminal equipment, but the partner does
have two separate phone lines, one of which is connected
to a fax machine. The service of the present invention
can be used by the worker to split the calls within the
public switched telephone network, placing the voice
call to the partner on the proper line and a fax call to
the other line.
4) A network trouble-shooter receives a voice
call from a customer having trouble accessing the
network, which is remote from the customer. Both people
have multi-call terminal equipment capable of using the
system of the present invention. While talking to the
customer, the trouble-shooter could access the network
and determine the problem and then resolve it. The
customer could be directed to access the network without
hanging up with the trouble-shooter. When the customer
is satisfied that the problem has been resolved, each
party can then relea~e both calls.
5) A person at home could be talking to someone
on a voice call. While this is occurring, someone in
the same home can place a second call using the same
phone line and number. The two calls can be to
different destinations.
Many other examples could occur as necessary and as
the user of the system of the present invention
determines are necessary.
It is to be understood that the above description
is only one preferred embodiment of the invention.
Numerous other arrangements may be devised by one
skilled in the art without departing from the spirit and
cope of the invention.
