Telephonic communications – Plural exchange network or interconnection – Interexchange signalling
Reexamination Certificate
1998-05-01
2001-05-22
Smith, Creighton (Department: 2642)
Telephonic communications
Plural exchange network or interconnection
Interexchange signalling
C379S220010, C379S207030
Reexamination Certificate
active
06236722
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the completion of voice connections in a switched telephone network, and in particular to the completion of voice connections in a switched telephone network using a data request message for initiating the voice connection and TCAP common channel signaling messages as required to determine the availability of a voice terminal involved in the call.
BACKGROUND OF THE INVENTION
Computer telephony integration products are well-known and widely used to provide personal as well as corporate telephone services. The use of computer telephony integration products permits enhanced dialling and call handling features. A shortcoming of such products is that those features are enabled outside the Public Switched Telephone Network (PSTN). Consequently, call completions effected using such products often use redundant circuits in the PSTN. Efficiency is therefore sacrificed. A further disadvantage of such products is that they have no access to the signaling network which controls the PSTN. Consequently, such products are incapable of determining the status of a remote user line or querying PSTN nodes to obtain information useful in call setup or call direction. There therefore exists a need for computer telephony integration products that are more completely integrated with the PSTN.
Another commonly used system in the PSTN are call centers which offer customer support, help lines, or the like. Such centers typically use an out-dialer to set up calls to a predetermined list or queue of numbers which are to be called. To improve performance, algorithms have been developed to predict when an agent will become available to take a call, and calls are placed in advance of agent availability. If a number dialled is not answered, the number is moved to a bottom of the queue and retried when it has advanced again to the top of the queue. Due to the fact that such dialers have no access to the PSTN signaling network, it is difficult or impossible to write algorithms to accurately and consistently determine the reason that any particular call is not answered when dialed. Consequently, calls may be attempted many times over even though there is no probability of reaching the called party. This wastes transport and signaling facilities and ties up resources that could be profitably used by others. There therefore exists a need for better out-dialer facilities for call centers.
In the applicant's co-pending patent application described above, a method and a system for completing voice connections between voice terminals in a Switched Telephone Network (STN) using the flexibility of computer control exercised through a data network independently of voice terminals connected to the network was disclosed. The method and system provide several advantages over prior art methods of completing voice connections. First, it provides all the advantages and flexibility of computer control, including automated dialling from electronic telephone books or directories. It also provides the advantage of sequential calling without disconnection of the calling party so that a plurality of sequential calls may be completed without interrupting the user's voice connection with an originating switching point (SP) in the STN.
The system disclosed in applicant's co-pending application includes a Virtual Switching Point (VSP) which is a physical node in the signaling network of the STN and a virtual node in the transmission network of the STN. The VSP is enabled to receive call request messages from a data network such as a local area network (LAN), a wide area network (WAN), an Intranet or the Internet. The VSP processes the call request which may include more than one called number. A call request is processed by sending a common channel signaling message from the VSP to an SP in a local calling area of the calling party to initiate a voice connection with the calling party. After the connection is established with the calling party, a second common channel signaling message is sent to a switching point in the STN to initiate a connection with the called party. The two connections are the first and second legs to the same call. The voice connections may be local or long distance voice connections.
While this system provides significantly improved functionality over the computer-integrated telephony systems of the prior art, and capitalizes on the inherent switching capability of the PSTN, it does not capitalize on the inherent query capability of a common channel signaling network. In particular, the common channel signaling system, Signaling System 7 (SS7) provides a query signaling capability known as Transaction Capability Application Part (TCAP) signaling. TCAP signaling provides a powerful query tool which may be used by physical nodes in an SS7 network.
There therefore exists a need for call completion systems which use the inherent switching power resident in the PSTN as well as the inherent query capability resident in the common channel signaling network that controls the PSTN.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method for using TCAP signaling for improved call setup from a Virtual Switching Point in a Switched Telephone Network.
It is a further object of the invention to provide a method using TCAP signaling messages which originate from a signaling node in the STN for improved call setup.
It is another object of the invention to provide a method for using TCAP signaling messages in an STN to determine the availability of a calling party's voice terminal in order to minimize Integrated Services Digital Network User Part (ISUP) signaling during initial call setup.
It is yet a further object of the invention to provide a system for using TCAP signaling for improved call setup from a Virtual Switching Point (VSP) in an STN in which the VSP is a physical node in the signaling network and a virtual node in the transmission network of the STN.
It is another object of the invention to provide a system for using TCAP signaling for improved call setup from a VSP wherein the TCAP signaling is used to determine the availability of a called voice terminal when a first attempt to call that voice terminal indicates that the voice terminal is busy.
It is yet another object of the invention to provide a system for using TCAP signaling for improved call setup for a call center where a plurality of predetermined call requests must be completed.
The invention therefore provides a method of completing a voice connection between a first and second voice terminal on a Switched Telephone Network (STN), comprising the steps of:
receiving at a Virtual Switching Point (VSP) in the STN having a connection to a data network a call request message;
sending a query message to an SP in the STN that serves the calling party to determine the availability of a calling line identified in the call request;
if a response to the query message indicates that the calling line is available, sending a first Common Channel Signaling (CCS) message from the VSP over a signaling network of the STN to an SP in the STN to initiate a first leg of the voice connection, and
sending a second CCS message from the VSP to an SP in the STN to initiate a second leg of the voice connection, the first and second CCS messages being interrelated to an extent that a circuit identification code in each message is associated with opposite ends of the same facility.
In particular, the invention provides a method for using TCAP signaling for improved call set up from a virtual switching point (VSP) in a switched telephone network (STN), comprising:
receiving through a data network a call request message at the VSP, the call request message indicating a calling party number and at least one called party number;
sending a TCAP query message through a common channel signaling system of the STN to a switching point (SP) which serves the calling party number to determine when the calling party number is available to receive a call in response to the message; and
on receipt of a
Gilbert Gordon J.
Williams L. Lloyd
Bell Canada
Smith Creighton
Thomas Kayden Horstemeyer & Risley, L.L.P.
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