Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD AND DEVICES FOR BRIDGING DATA AND TELEPHONE NETWORKS
FIELD OF THE INVENTION:
The present invention relates to networked computing
devices, and more particularly to a method and devices for
bridging data and telephone networks.
BACKGROUND OF THE INVENTION:
Traditionally, telephone calls have been routed through
the public switched telephone network ("PSTN") to interconnect
subscribers wishing to speak with each other.
More recently, data networks have become commonly used to
exchange data between interconnected computing devices. The
best known example of such a network is the public Internet.
In the presence of a data network and the PSTN, the desire
to bridge traffic on one network to the other has been
recognized, For example, the PSTN is often used to provide
access to the data network.
Similarly, the use of a data network to carry voice
traffic has also been recognized. Accordingly, computer
applications that allow end-users to establish voice
connections using a data network are known.
Additionally, the use of a data network to transparently
carry calls between end-users on the PSTN is also known. This
is often done to avoid toll charges associated with the PSTN.
Finally, the bridging of calls originating with a caller
on the telephone network and an end-user at a data network has
also been recognized. This form of bridging is often performed
as a matter of convenience, and is often used when a telephone
connection is not available to the end-user resulting, for
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example, from the end-user's use of the telephone line to establish a
connection to the data network.
Devices used for this latter form of bridging are, for example,
disclosed in PCT patent publication no. WO 97/20424. However, such
bridging assumes that the data network offers sufficient capacity in
order to carry call data. In reality, a data network, such as the
public Internet is often congested and therefore cannot adequately be
used to carry voice traffic.
Accordingly, it would be desirable to provide a method and
devices for bridging calls across networks that allow users to the
flexibility of maintaining high quality call connections.
SUMMARY OF THE INVENTION:
In accordance with an aspect of the present invention there is
provided a method of providing a telephone call from a telephone
network to a user proximate a computing device interconnected with a
data network, the method comprising the steps of: a) receiving an
indicator of the call at a gateway in communication with the data
network and the telephone network; b) dispatching a notification of
the call from the gateway far the computing device; c) bridging the
call from the telephone network to the computing device using the data
network, to form a bridged call and enable communication with the call
using the computing device; and d) in response to a specified
condition, forwarding the call to a telephone line interconnected with
the telephone network, after step c).
In accordance with another aspect of the present invention there
is provided a telephone network to data network gateway comprising: a
processor; a telephone network interface in communication with the
processor and the telephone network; a data network interface in
communication with the processor and the data network; persistent
storage memory in communication with the processor, the persistent
storage memory storing processor executable instructions adapting the
gateway to: a) receive a telephone network call at the telephone
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network interface; b) dispatch a notification of the call from the
data network interface to a computing device over the data network; c)
cause the call to be bridged from the telephone network to the
computing device using the data network, to form a bridged call
enabling a user at the computing device to communicate with the call
using the computing device; and d) in response to a specified
condition, cause the call to be forwarded to a telephone line
interconnected with the telephone network, after the call has been
bridged.
In accordance with a further aspect of the present invention
there is provided a method of operating an end-user computing device
interconnected with a data network, the method comprising the steps
of: a) receiving over the data network an indicator of an incoming
call at a telephone network; b) communicating with the call at the
telephone network via the data network using a voice telephony
application; and c) in response to a specified condition, notifying
the gateway to forward the call to a telephone line on the telephone
network, after step b)
In accordance with yet a further aspect of the present invention
there is provided a computing device comprising: a processor; a data
network interface in communication with the processor and the data
network; persistent storage memory in communication with the
processor, the persistent storage memory comprising processor readable
instructions adapting the device to: a) receive a notification of a
call at the telephone network, at the data network interface; b)
communicate with the call at the telephone network by way of the data
network using a voice telephony application; and c) in response to a
specified condition, transmit an indicator to the gateway to transfer
the call to a telephone interconnected with the telephone network,
after communications with the call.
In accordance with another aspect of the present invention there
is provided a data network to telephone network gateway comprising: a)
means for receiving an indicator of the call at a gateway in
communication with the data network and the telephone network; b)
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means for dispatching a notification of the call from the gateway for
the computing device; c) means for bridging the call from the
telephone network to the computing device using the data network, to
form a bridged call that enables the user to communicate with the call
using the computing device; and d) means for forwarding the call to a
telephone line interconnected with the telephone network in response
to a specified condition received after bridging the call from the
telephone to the computing device using the data network.
In accordance with another aspect of the present invention there
is provided a computer readable medium storing computer software that
when loaded by a gateway comprising a telephone network interface,
adapts the gateway to: a) receive an indicator of the call at the
gateway computer at the telephone network adaptor; b) dispatch a
notification of the call from the gateway computer for a computing
device interconnected with a data network; c) cause the call to be
bridged from the telephone network to the computing device using the
data network, to form a bridged call and enable communication with the
call using the computing device; and d) in response to a specified
condition, cause the call to be forwarded to a telephone line
interconnected with the telephone network, after causing the call to
be bridged.
In accordance with another aspect of the present invention there
is provided a method of processing a call comprising the steps of: a)
bridging the call between a telephone network and a computing device
in communication with a data network, at a gateway in communication
with the data network and the telephone network, to form a bridged
call that enables a user to communicate with the call using the
computing device; and b) in response to a specified condition,
forwarding the call
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to a telephone line interconnected with the telephone network,
after step a) .
BRIEF DESCRIPTION OF THE DRAWING:
In figures which illustrate, by way of example,
embodiments of the present invention,
FIG. 1 illustrates a plurality of interconnected
computing devices, including a data network to telephone
network gateway and an end-user computing device,
exemplary of embodiments of the present invention;
FIG. 2 is a block diagram of an architecture of a gateway
of FIG. 1;
FIG. 3 illustrates an organization of memory of the
gateway of FIG. 2;
FIG. 4 illustrates an architecture of an end-user
computing device, illustrated in FIG. l;
FIG. 5 illustrates an organization of memory of the
device of FIG. 4; and
FIGS. 6A, 6B and 7 illustrate steps in methods exemplary
of embodiments of the present invention.
DETAILED DESCRIPTION:
FIG. 1 illustrates a plurality of computing devices 14,
16, 18 and 26 interconnected to each other by way of data
network 10. Network 10 is preferably a packet switched data
network, and is preferably the public Internet, using the
Internet protocol ("IP"), as detailed in RFC 791 to exchange
data in the form of packets between interconnected computing
devices, such as computing devices 14, 16, 18 and 26. Network
10 may, for example, be the public Internet, a private
Internet, or another suitable local or, wide area network.
Each computing device 14, 16, 18 or 26 may be a network
server, used to serve files such as data, applications, or an
end-user workstation or terminal that makes use of other
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network resources. In the illustrated example, devices 14 and
26 are end-user work stations; device 18 is an Internet service
provider server ("ISP"); and device 16 is a message server and
data network to telephone network gateway, exemplary of an
embodiment of the present invention.
Devices 14, 16, 18 and 26 may be interconnected with
network 10 in any of a number of ways. For example, device 14
may be directly interconnected with an Internet router using
an Ethernet or other physical interface. Device 26 may be
connected to network 10 through the PSTN 12. Similarly, devices
16 and 18 could be connected to network 10, by an asynchronous
transfer mode ("ATM") switch (not illustrated); an integrated
standards digital network ("ISDN") (not illustrated); a local
area network (not illustrated); or any other suitable physical
connection to network 10.
Device 26, ISP 18 and gateway 16 are further
interconnected with a telephone network, which, in the example
embodiment network is the public switched telephone network
("PSTN") 12. An additional example PSTN subscriber 39 is also
illustrated.
As illustrated, computing device 26 may be connected with
network 10 through ISP 18 by way of the PSTN 12. As noted,
device 26 is an end-user workstation. A conventional telephone
modem preferably forms part of computing device 26. The modem
is interconnected with PSTN 12 using a conventional telephone
line 34 to central office switch ( "CO" ) 32, forming part of the
PSTN 12. Telephone line 34 is also used to provide service to
telephone 28 when line 34 is otherwise not in use. Connection
of computing device 26 to network 10 is typically not
permanent, but instead is initiated over PSTN 12 for sessions
of varying duration.
ISP 18 comprises a processor 36 in communication with a
bank of modems 38 interconnected to PSTN 12 through trunk 23
to CO 24 and a network interface 37, such as a T1 data
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interface, Ethernet interface, or the like, connecting ISP 18 to
network 10. ISP 18 provides subscribers with Internet access
through the PSTN 12. Subscribers gain access to network 10 by
dialing a PSTN dial number ("DN") identifying trunk 23 and
interconnected to modem bank 38 and establishing an IP session using
conventional software at ISP 18, as detailed below. Modem bank 38
comprises a plurality of modems, typically interconnected with
individual telephone lines all forming part of trunk 23 assigned to
a single DN so that multiple calls to the DN assigned to the ISP 18
are directed to different modems within modem bank 38.
Gateway 16, on the other hand, is a message server and
telephone network to data network gateway, that is interconnected to
network 20 using any one of a number of known physical connections.
Gateway 16 is adapted to provide an Internet service at almost all
times. As such, connection of gateway 16 to network 10 is typically
not intermittent and is instead permanent. Gateway 16 is preferably
connected with network 10 using dedicated a T2 or fractional T1
interface. Gateway 16 is further interconnected with the PSTN 12,
through CO 20, as illustrated. As will become apparent, gateway 16
is preferably adapted to provide a service such as the Internet call
waiting service, as for example disclosed Canadian Patent
Application Number 2,263,264. Gateway 16 is further adapted to
bridge calls between network 10 and PSTN 12.
An exemplary architecture of gateway 16 is illustrated in FIG.
2. Gateway 16 is typically a conventional server suitable computing
device. Gateway 16 may for example be a SUNS' Sparc server; a
Microsoft~ NT Server; a Hewlett PackardT'" HPUX server, or the like.
Gateway 16 comprises a processor 40, in communication with
persistent storage memory 42, and data network interface 44 and a
PSTN interface 46. As well, gateway 16 may comprise a display 48
and input device 50, such as a keyboard, mouse or the like.
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Processor 40 comprises a conventional central processing unit,
and may for example comprise a microprocessor in the INTEL~ x86
family. Of course, processor 40 could be a RISC based CPU; a
Motorola° CPU, or any other suitable processor known to those
skilled in the art. Persistent storage memory 42 comprises a
suitable combination of random access memory, read-only-memory, and
disk storage memory used by processor 40 to store and execute
programs adapting the gateway 16 to act as an Internet message
server and gateway, as detailed below. Persistent storage memory 42
may include a device capable of reading and writing data to or from
a computer readable medium 45 used to store software and data to be
loaded into memory 42. Network interface 44 comprises any interface
suitable to physically link gateway 16 to network 10. Interface 44,
may for example be an Ethernet, ATM, or ISDN interface or even a
modem that may be used to pass data, in the form of packets from and
to the remainder of network 10. As noted, interface 44 is
preferably a T1 or fractional T1 interface. PSTN interface 46 is
preferably an ISDN primary rate interface ("PRI") comprised of PSTN
access card supporting the appropriate PRI standards, available from
for example, Dialogic~ Corp. of Parsippany, NJ., 07054, or Brooktrout
TechnologyT"" Inc. of Needham, MA, that receives calls and extracts
caller information and passes this to processor 40, as detailed
below.
The organization of persistent storage memory 42 of gateway 16
is illustrated in FIG. 3. Stored within memory 42 are computer
software programs and data that are loaded into working memory of
gateway 16 permit gateway 16 to be operable as a message server. As
illustrated, memory 42 stores operating system software 52;
application software 54; and data 56. Operating system software 52
may, for example, be Microsoft~ NT Server operating system software,
UNIX operating system software, or the like. Application software
54 includes network interface software 58, which typically includes
an Internet protocol suite allowing communication of gateway 16 and
thus operating system 52 with network 10,
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through physical data network interface 44 (FIG. 2).
Application software 54 further comprises a network message
server and gateway application 64, including a data network
telephony application 60.
Preferably, and in addition, forming part of application
software 54 is a database application or engine 62, such as for
example a structured query language ("SQL") database engine
capable of retrieving, updating, deleting and otherwise
operating on records stored within a database 68. Database 68
stores records representative of end-users served by gateway
16 in accordance with the present invention. Other applications
66 and data 70 may also be stored within memory 42. As will
be appreciated application software 54 may be formed by
standard programming techniques known to those skilled in the
art.
FIG. 4 illustrates, in block diagram, the architecture of
computing device 26 used by an end-user. Computing device 26
is a typical home or office computer comprising a processor 86,
in communication with persistent memory 90, a network interface
such as modem 88, a display 92, an audio interface 84;
microphone 80 and typically at least one input device 94.
Processor 86 is a typical central processing unit and may be
a processor in the INTEL x86 family. Persistent memory 90
preferably comprises a hard drive, RAM and ROM memories . Modem
88 is typically a conventional telephone modem such as for
example a U. S . RoboticsT"" SportsterT"" or equivalent modem. Audio
interface 84 is interconnected with speaker 82 and microphone
80. Audio interface 84 may be a conventional computer sound
card including an analog to digital, and digital to analog
converter allowing sampling of sound through a microphone 80
and replay of sound through speaker 82.
The organization of persistent storage memory 90 of device
26 is illustrated in FIG. 5. As with memory 42 of gateway 16,
stored within memory 90 are computer software programs and data
that are loaded into operating memory of device 26. These
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permit device 26 to be operable as an end-user work station. As
illustrated, memory 90 stores operating system software 96;
application software 98, and data 100. Operating system software 96
may, for example, be Microsoft~ Windows NT Workstation operating
system software; Windows 3.1, 95 or 98 software; Apple System 7.5
operating system software; or the like. Application software 98
includes network interface software 104, which also typically
includes an Internet protocol suite allowing communication of
computing device 26 over modem 88 (FIG. 5) and thus operating system
96 with network 10 (FIG. 1). Application software 98 further
comprises a modem dialer 106 that operates modem 88 to establish
temporary connections to data network 10 via PSTN 12, as detailed
below. Application software 98 additionally comprises messaging
application 102 and network telephony application 110. Application
software 98 may further comprise end-user applications 108 such as
an Internet browser, and other applications otherwise employed by
the end-user and operator of device 26. Again, application software
98 may be formed using conventional programming techniques known to
those skilled in the art.
Telephony applications 60 (FIG. 3) and 110 (FIG. 5) may for
example comprise Microsoft° Netmeeting'" software, available from
Microsoft Corp. of Redmond, WA, that enables voice over Internet
protocol communication ("VOIP"), as for example detailed in
Internation Telecommunications Union ("ITU") Recommendation H.323.
With reference to FIG. 1, in operation, an end-user at device
26 "registers" with gateway 16 in order to obtain service from
gateway 16. An example registration process is detailed in Canadian
Patent Application No. 2,246,136, entitled, Network Interconnected
Computing Device, Server, and Notification Method, filed August 31,
1998 and naming Carl Potvin as inventor.
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At a later time, the end-user at device 26 establishes an
Internet connection through PSTN 12. An Internet connection is
typically established through PSTN 12 by running or launching dialer
application 106 at device 26; establishing a PSTN circuit between
computing device 26 and ISP 18; and establishing a data connection
between modems at bank 38 of ISP 18 and device 26. Once the data
connection is negotiated and established, ISP 18 prompts computing
device 26 for an identifier and/or password using conventional
software (not illustrated) stored at ISP 18. Dialer 106 typically
provides such an identifier and/or password. Upon successful
provision of a password and identifier, ISP 18 and computing device
26, next, negotiate an IP link to computing device 26. This link
may, for example, be established by a serial line Internet protocol
("SLIP") or a point-to-point protocol ("PPP") IP connection between
device 26 and ISP.
As part of establishing this IP link between computing device
26 and ISP 18, ISP 18 may assign a temporary "session" IP address to
the computing device 26. This session IP address now uniquely
identifies computing device 26 on network 10 and allows IP packets
to be directed to computing device 26 during this session. Device 26
may register with gateway 16, by providing gateway 16 with an
indication over network 10 using the known IP address of gateway 16,
that computing device 26 is network interconnected ("on-line"), and
the session IP address of device 26, as detailed in the above
Canadian Patent Application No. 2,246,136 filed August 31, 1998, and
naming Carl Potvin as inventor. This session network address is
preferably stored within memory 42 of gateway 16. Alternatively,
the session network address of device 26 may be provided to gateway
16 using the known ITU H.323 Recommendation.
Once the end-user device 26 has registered with gateway 16, IF
packets containing data may be forwarded by gateway 16 to the end-
user device 26, using the session IP address stored at gateway 16.
As will be appreciated by those skilled in the
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art the packets may, for example, be directed to a logical
network port, so that the packets are processed and interpreted
by messaging application 102 and telephony application 110
executing at device 26 (FIGS. 4-5).
In an exemplary embodiment, gateway 16 acts as an Internet
call waiting server and gateway. Gateway 16 forwards messages
over network 10, to end-users such as the end user at device
26 indicating PSTN callers attempting to reach an end-user at
device 26 whose PSTN line is occupied as a result of the
Internet connection through telephone line 34. Specifically
CO 32 provides the known call forward busy ("CFB") service,
redirecting calls directed to the PSTN dial number of telephone
28 to another programmable number. CO 32 is preferably pre-
configured so that the CFB feature for end-user at device 26
redirects calls to PSTN interface 46 of gateway 16 by way of
CO 20, in the event that telephone line 34 is busy or in an
off-hook state. Calling number information associated with the
call, including the called number and a caller's phone number
and name, is also passed to interface 46 of gateway 16, where
it may be processed by processor 40.
Exemplary steps 600 performed by gateway 16 if PSTN
subscriber 39 attempts to call an end-user over line 34 while
line 34 is in use to connect device 26 to ISP 18 are
illustrated in FIG. 6. Exemplary steps 700 performed at device
26 are illustrated in FIG. 7. As illustrated, the call,
forwarded by CO 32 to interface 46 of gateway 16 is received
in step 5602. Upon receipt of such a call, gateway 16 holds
the call at interface 46. Gateway 16 also compares the called
number with DN entries in database 68. If a corresponding end-
user is not "on-line" the call may be forwarded to a voice mail
system (not shown) or network busy tone.
If a corresponding end-user is "on-line", as determined
in step 5604, gateway 16 dispatches a notification message in
step 5608 indicating that a caller such as subscriber 39 is
attempting to dial the busy telephone line 34, as well as an
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indicator of the calling number over network 10 to computing device
26, using the session network address for computing device 26,
stored. within memory 42. The notification message may, for example,
be dispatched using a low latency network protocol as disclosed in
Canadian Patent Application No. 2,246,134 entitled "Enhanced
Network Protocol" filed August 31, 1998, naming Marc Carrier as
inventor. The notification message is received at device 26 in step
S702 (FIG. 7) and causes messaging application 102 to produce a user
perceptible indicator at device 26 in step 5704. The indicator may
be an audible sound generated at speaker 82, and/or a visual
indicator at display 92. The visual indicator may contain
information about the incoming call, including caller ID
information. As well, application 102 may cause a number of end-
user call disposition choices to be presented at display 92 (FIG. 3)
of device 26 in step 5706. These end-user disposition choices may
include the following:
A. disconnect network connection and accept call over the
PSTN;
B. send call to network voice mail system;
C. send pre-recorded message to caller;
D. forward call to alternate DN; and
E. accept call as voice over IP call.
In response, the end-user may select one of the presented
choices to process the call, to application 102 in step S708.
Device 26 forms an appropriate response message which is forwarded
to gateway 16 using network 10 and for example, the above described
low latency protocol, as detailed below. Gateway 16, processes the
call in accordance with the response message received from device
26. If a response is not received by gateway 16 within a specified
time as determined in step 5610 and 5612, the call is disposed of
by, for example, being forwarded to another network resource such as
a voice mail system or a network busy tone, in step 5614.
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If the end-user selects choice A., as determined in steps
5710 and 5712, device 26 dispatches an appropriate message to
gateway 16, preferably waits for acknowledgment of the message,
and then disconnects the PSTN Internet connection in step 5714.
Gateway 16, receives the message and in turn, in steps 5616 and
5618 uses interface 46 to forward the call to the end-user DN
thereby establishing a PSTN circuit with the end-user's PSTN
line 34 and causing handset 28 to ring. If the call is not
accepted by the end-user it is disposed of by CO 32 in a
conventional manner.
If the end-user selects choice B., device 26 forwards an
appropriate message to gateway 16, in step 5714. Gateway 16,
in response, forwards the call directly to the end-user' s voice
mail server ("VMS") (not illustrated) in steps 5620 and 5622
where the caller 39 is prompted with the usual options to leave
a message that may later be heard by the end-user. Of course,
this option is typically only available if the end-user
subscribes to network voice mail services.
If the end-user selects choice C., device 26 dispatches
an appropriate message over network 10 to gateway 16 in step
5716. Gateway 16, in response in steps 5624 and 5626 generates
a pre-selected voice message over interface 46 to the caller.
As will be appreciated, the pre-selected message may be pre-
recorded or synthesized and is typically stored within memory
42. Thereafter, gateway 16 will typically disconnect the call.
If the end-user selects choice D., device 26 dispatches
an appropriate message over network 10 to gateway 16 in step
S714. This message may include an alternate PSTN DN that was
previously input by the end-user at device 26. Alternatively,
an alternate PSTN DN may be stored at gateway 16. In any
event, upon receipt of the message at gateway 16 as determined
in steps 5628 and 5630, gateway 16 establishes a connection
with the alternate PSTN DN and forwards the call held at
interface 46 to this DN in step 5630. Once forwarded to the
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alternate DN, the call is processed in a conventional manner.
If the end-user selects choice E., as determined in step
5710, gateway 16 in steps 5632 initiates and maintains an
Internet telephony session with device 16 using network
telephony application 60 by bridging the call on hold at
gateway 16 with device 26 under control of application 110.
Device 26, in turn initiates an Internet telephony session
using application 110 in step 5710. The end-user at device 26
is now able to conduct a voice telephony session with caller
39, via gateway 16 and data network 10 using microphone 80 and
speaker 82 (FIG.4).
If choice E. is selected, and as will be appreciated by
those skilled in the art, telephony applications 60 and 110 at
gateway 16 and device 26 exchange voice data by sampling speech
and thereafter encoding this sampled speech into data using a
known voice compression algorithm, such as for example, those
compression algorithms detailed in ITU recommendations 6.721,
722, 723.1, 728 or 729 in compliance with ITU recommendation
H. 323. The encoded data is encapsulated in IP compliant
packets and exchanged over network 10 in steps 5718 and 5632.
Once received, the data is extracted by application 60 or 110,
decompressed and preferably replayed by processor 40 or 86 at
PSTN interface 46 or audio interface 84. In order to ensure
real-time communication over network 10, applications 60 and
110 typically utilize the uniform datagram protocol ( "UDP/IP" ) ,
as detailed in RFC 768 in order to exchange packets containing
the voice data over network 10. As UDP/IP does not ensure
delivery of packets, nor correct ordering of delivered packets,
packets may be (and typically are) lost. This packet loss
results in decreased voice quality in the bridged call between
caller 39 and the end-user at device 26. Delays in packet
transmission result in similar decreased voice quality. If too
many packets are lost or delayed the voice quality of the
bridged call becomes unacceptable. Alternatively, even if a
reliable network protocol that ensures delivery of packets
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(such as the transmission control protocol ("TCP/IP") detailed
in RFC 793) is used, network delays may result in unacceptable
voice quality. The particular threshold at which the voice
quality becomes unacceptable will typically vary depending on
the compression algorithm used, and the perception of the end-
user.
Accordingly, in step 5720 telephony application 110 and/or
messaging application 102 at device 26 may monitor the number
of packets that are lost. Alternatively or additionally,
messaging application or gateway application 64 could monitor
the number of lost packets and periodically provide an
indicator of this number to device 26. Messaging application
102 may further display a measure of the number of lost packets
on display 92 at either device 26 or server 16. This may be
particularly useful, as the number of lost packets lost at
device 26 and lost at server 16 may differ. An end-user at
device 26 may therefore not be aware of a deterioration of call
quality, perceived by a caller such as PSTN subscriber 39. If
the number of lost packets/unit time at either server 16 or
device 26 exceeds a pre-defined threshold, application 110
could optionally automatically cause the call to fall-back to
the PSTN 12. Similarly, if the number of packets/unit time
falls below a pre-defined threshold, as a result of delays,
application 102 or 110 could cause the call to fall-back to the
PSTN 12. That is, application 64 re-routes the bridged call
and routes the call over PSTN 12.
Specifically, in causing a bridged call to "fall-back" to
the PSTN 12, messaging application 102 sends a "fall-back"
message indicating it wishes to initiate a PSTN fall-back to
gateway 16 in step 5722. Gateway 16, receives the fall-back
message in step 5638, and discontinues maintaining the VOIP
session in step 5636 and acknowledges receipt of the fall-back
request in step 5640. This acknowledgment is received at
device 26 in step 5726. Device 26, under control of messageing
application 102, in turn generates another audible or visible
notification of the acknowledgement. Thereafter, device 26 may
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automatically disconnect the PSTN connection to ISP 18 in step
5728. Alternatively, an end-user at device 26 may initiate the
disconnection through application 102 or otherwise, in response
to the notification.
At about the same time, gateway 16 maintains the call at
PSTN interface 46 on hold. Optionally, gateway 16 may play an
audible message to PSTN subscriber 39 advising that the call
is being transferred. This message may also be stored in
memory 42 of gateway 16. Gateway 16 then initiates a PSTN
connection to the DN of line 34 using the original called party
information accompanying the incoming call, and transfers the
call to the hand-set of the end-user who may, in turn continue
the call in step 5642.
Specifically, server 16 preferably waits four seconds and
then initiates a new call to line 34. By that time messaging
application 102 at device 26 has likely received the
acknowledgment to its fall-back message and has disconnected
line. Preferably, the new call from server 16 to line 34
includes the calling number of the subscriber call, the called
number of line 34, as well as optional redirection signalling
information. When the call arrives at CO 32 line 34 may be busy
or idle. If the line is idle, the new call will terminate and
server 16 will receive an indication that the phone is ringing.
The subscriber call is then bridged with this new call and will
thus be able to speak with the end-user at line 34.
If line 34 has not been disconnected for device 26,
typically because application 102 has not released line 34, the
new call will encounter a busy line 34. This may occur, for
example, because of device 26 or due to delays arising from
delayed or lost packets before successful delivery of the
acknowledgement. As line 34 is subject to the CFB feature, the
call is redirected toward the server 16. By matching the
signaling information received with the forwarded call with
call state data for the subscriber (also optionally maintained
within memory 90), the server may identify that this is not a
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new call for the subscriber but a call that "bounced". It
therefore releases the new call. The subscriber call is
returned to PSTN interface 46 from which it originated. Server
16 then again waits four (4) seconds and re-attempts. This
process is repeated a number of times or for a set duration
before abandoning or until the subscriber hangs-up. If all
attempts are unsuccessful, the call is routed to an
announcement, produced for example at server 16, indicating
that the subscriber at line 34 is not available or to the
subscriber's network voice mail server.
As an enhancement, in some PRI signaling protocols, server
16 can indicate that calls made should be cleared if they
encounter further redirections (e.g., such as would occur by
encountering CFB). This is, for example, possible with the
DMS-100 NI-1 PRI protocol. When this protocol is used, server
16 performs this request. If line 34 is busy, the call is not
forwarded to server 16 but is cleared towards the server 16.
Using the signaling information received, server 16 may detect
this condition and initiate the four (4) second delay prior to
re-attempting. This has the advantages of reducing the network
and server resources required during the re-attempt process.
As will be appreciated the described substeps forming part
of step S642, used to route a call to line 34 could similarly
be used to transfer a call in response to choices A, or D.
Alternatively, the call could be routed to an alternate
DN after the PSTN fall-back is initiated. This DN might be the
DN of the end-users voice mail system, or a DN contained in the
message used to initiate the fall-back.
In an alternate embodiment, the above described fall-back
method could additionally or alternatively be used with voice
over IP initiated calls, if telephony applications 60 and 110
facilitated such outgoing voice over IP calls. That is, for
example, if after an end-user at device 26 established an
Internet session with ISP 18 and wished to place a call to a
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PSTN line of subscriber 39, application 60 could send
appropriate signalling information to server 16 directing
application 110 and server 16 to initiate a PSTN call to dial
number of subscriber 39; initiate a voice over IP call at
application 60 and device 26; and then bridge this PSTN call
with the device 26. Thereafter, applications 60 and 110 could
optionally monitor the quality of the bridged call and allow
an automated or end-user initiated fall back to the PSTN, as
described above with reference to steps 5632 and S718 to 5728.
Server 16, would accordingly place the call connection to the
PSTN line of subscriber 39 on hold, initiate a call to the
subscriber at line 34, and thereafter transfer the call on hold
to line 34.
From the above description, it will be appreciated that
device 26, ISP 18 and gateway 16 are all preferably
independently operated. As will be appreciated, however, ISP
18 and gateway 16 could be co-located.
Further, while in the described embodiments, the gateway
16 performs call bridging and data network messaging, a person
skilled in the art will appreciate that these functions need
not be performed by a single device. Instead, the gateway 16
might only receive an indicator of a call at the telephone
network. Similarly, the gateway 16 might be in communication
with another network connected device that bridges the incoming
call over the data network, and another network connected
device that signals end-user device 26 of the incoming call
received at the gateway 16.
While the above embodiment has been described in the
context of a temporary connection to network 10 using the PSTN
12, a person skilled in the art will appreciate that the
described embodiments could easily be modified to accommodate
other temporary or permanent data network connections, by way
of, for example a wireless network, an ISDN connection, an
asynchronous digital subscriber line ("ADSL") connection, or
another connection known to those skilled in the art. In such
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a modified embodiment, a telephone call would not necessarily
be transferred to the same telephone line used to establish the
Internet connection, but would be transferred to a PSTN line
elsewhere, and preferably proximate the end-user. As well,
while the above embodiment has been described with reference
to a single end-user, a person skilled in the art will
appreciate that gateway 16 will typically provide similar
services to a large group of end-users. As will be further
appreciated, gateway 16 could be used in association with an
advanced intelligent network ("AIN"). As such, an AIN
redirection service could be used instead of the described CFB
feature .
Additionally, while the organization of software and data
components at device 26 and gateway 16 has been illustrated as
clearly delineated, a person skilled in the art will appreciate
that the delineation between applications, network interface
software and operating system software is somewhat arbitrary.
Other arrangements of such software are possible. For example,
network interface software 104 and 58 may form part of
operating system software 52 or 96. Similarly, while the
embodiments have been described using the specific IP, and
UDP/IP protocols other similar protocols, such as for example
the IPX and SPX protocols could be used.
It will be further understood that the invention is not
limited to the embodiments described herein which are merely
illustrative of a preferred embodiments of carrying out the
invention, and which are susceptible to modification of form,
arrangement of parts, steps, details and order of operation.
The invention, rather, is intended to encompass all
modifications within its spirit and scope, as defined by the
claims.
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