JP2000165515A - Call setting synchronizing method for focused electric communication network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To synchronize the different networks with each other to prevent the call clipping and to improve the call processing efficiency in an electric communication system where the different networks are connected to each other by delaying the message that is received via a virtual transport. SOLUTION: When a subscriber telephone set 112 calls a telephone set 178 and a signal transfer point 140 receives a call establishing signal message, a virtual transport server 150 stores a common channel signal message in a memory 182. When a prescribed time passed, a packet data network 190, i.e., a different network decides the establishment of a voice path between the calling and called sides and transmits a message to perform a call setting operation. Thus, the common channel signal message is delayed to establish a voice path before a call setting process is executed. As a result, the call setting operation is surely attained between the different electric communication network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to telecommunications networks and, more particularly, to a method and system for efficient call processing when different telecommunications networks are used.

[Prior art]

[0002] The public switched telephone network (PSTN) consists of a number of central office switches for distribution to subscriber local lines and trunks, a small number of transit switches connecting the central office switches, a central office switch and transit switches. A plurality of interconnected analog and digital communication paths, an optional database for storing information, and a common channel signal (CCS) for message transmission used in switches to establish call connections.
System (common line signal system).

The common channel signaling system is a highly efficient and reliable component of the public switched telephone network. More specifically, a common channel signaling system comprises a number of interconnected signal transfer points for relaying messages between network nodes, and provides for call connections (i.e., calling and called parties) in a public switched telephone network. Establish, manage, and release a route that interconnects The common line signaling system sets up a call from an originating central office switch (ie, a central office switch delivering to the calling party) to a destination central office switch (ie, a central office switch delivering to the callee side). The call is typically sent by the originating switch on the call path following a common channel signaling system message that is relayed between the originating switch, other network nodes, and the destination switch. In a traditional public switched telephone network, a call connection between an originating switch and a destination switch is completed by a series of switch "handoffs" of the call in an established trunk connection.

Recently, telecommunications service providers have begun to use packet data networks, such as Internet Protocol networks and Asynchronous Transfer Mode Networks (ATMs), to establish call connections. In many cases, telecommunications service providers still use these packet data networks as transmission components in telecommunications networks that use public switched telephone network equipment. The result is a "focused" telecommunications network that includes a traditional central office switch coupled to a different packet data network.

A converged network allows a telecommunications service provider to maintain existing public switched telephone network equipment while taking advantage of the technology in packet transmission. However, in focused telecommunications networks, it is expected that complex compatibility issues will often arise. Thus, in a new challenge faced by telecommunications service providers, it seeks to manage and solve the interface between traditional public switched telephone network equipment and other types of networks.

[0006]

However, it is known that the use of conventional common channel signaling systems can cause serious synchronization problems in focused telecommunications networks. This is because the common channel signaling system is a highly developed and highly effective system for transmitting call processing (or setting) messages. The rate at which common channel signaling messages are delivered (as a result of the function achieved) is higher than the rate of the voice path or "call connection" that most packet data networks establish between the calling and called parties. Currently quite fast. As a result, most users of the focused telecommunications network are experiencing clipping in the call.

[0007] Due to the signal capacity of the highly available common channel signaling system, call setup messages travel from the originating central office switch to the destination central office switch at a fairly high rate. When the call setup is complete, the callee hears the ring and goes off-hook to receive the call. However, usually
The call connection between the calling party and the called party has not been established in the packet data network. as a result,
The call receiver notices the ringing tone and goes off-hook before the call path is actually established. The caller starts the conversation, but the callee has not heard the beginning of the conversation because the call connection path has not yet been established. In other words, prior to the packet data network establishing the voice path connecting the caller and the callee, the common channel signaling system may use the first few words of the conversation to establish ringing and call setup. Is clipped.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for synchronizing a call setup in a converged telecommunications network according to the present invention comprises the steps of: The use of a common channel signaling system to delay the release of call setup messages until the end of the day resolves the lack of proper synchronization and the call clipping introduced by the focused telecommunications network, and achieves technical improvements in telecommunications technology Is done. Basically, when deploying these systems in a focused telecommunications network, it would be beneficial to reduce the efficiency of traditional common channel signaling systems.

In one embodiment, the originating central office switch is connected to a virtual transport server (V
TS), a packet data network, and a common channel signaling system to the destination central office switch. Regarding the arrangement of the virtual transport server in the telecommunications network, for reference, see James W. et al. Brochering
US patent application serial no. 08 /
613789 has a detailed description. Call setup messages sent via the common channel signaling system are intercepted, translated, processed, and stored by the virtual transport server. Thereafter, a call setup message is emitted by the virtual transport server based solely on the determination that a call connection has been established between the calling party and the called party. Establishing a call connection in a focused telecommunications network is, for reference, described in James P. Dunn, US Patent Application Serial No. 09/072809.

Advantageously, by delaying the release of the common channel signaling system message, the packet data network (or other network different from the traditional public switched telephone network) is initiated by the transmission of the common channel signaling message. A call connection can be established prior to or at the same time as ringing establishment or other event establishment.

[0011]

FIG. 1 is a simplified flow diagram of a focused telecommunications system according to an embodiment of the present invention. The converged telecommunications system 100 includes central office switches 110 and 160, packet circuit gateway devices 130 and 132, signal transfer points 140 and 142, virtual transport servers 150 and 1,
52, and a packet data network 190. Central office switches 110 and 16
0 is part of a larger public switched telephone network. Similarly, signal transfer points 140 and 142 are also part of a larger common line signaling system that works with the public switched telephone network. In some embodiments, more central office switches, signal transfer points, or virtual transport servers may be deployed.

[0012] A central office switch 110 (hereinafter a calling switch) handles a subscriber line 111 interconnected with a subscriber premises device 112. In the present embodiment,
The central office switch is a 5ESS switching system sold by Lucent Technologies. The originating switch comprises a processor 112 interconnected with a database 114 by a link 113. In addition, link 1
It comprises a signal interface 116 interconnected by 17 and a call connection interface 118, each of which is connected to the processor 112 by links 119 and 121. The signal interface 116 receives and transmits a message transmitted by the common channel signaling system. Call connection interface 118 establishes a call connection and interfaces with a packet circuit gateway. Further, an interface 122 for processing a signal from the subscriber line 111 is provided.

Packet circuit gateway 130 interconnects with originating switch 110 by link 197 and with packet data network 190 by link 193. Similarly, the packet circuit gateway 132
Interconnects the packet data network on link 195 and central office switch 1 on link 199.
Interconnected with 60. Packet circuit gateway 1
30 and 132 receive the message and serve as termination points for paging connection establishment in the packet data network. In this embodiment, the packet circuit gateway 130 and the packet circuit gateway 132 are arranged outside the central office switch.
In some embodiments, the packet circuit gateway function is incorporated in the switch. Here, it is assumed that all packet circuit gateways have a synchronous / asynchronous conversion function.

The central office switch 160 (hereinafter, destination switch) handles the subscriber line 177 interconnected with the subscriber premises equipment 178. Destination switch 160
Has a processor 162 connected to a database 164 by a link 163. Signal interface 16
6 is a link 165 and a call connection interface 168
And a processor 162 via link 169
Interconnected with Call connection interface 16
8 is interconnected to processor 162 by link 167. Further, a subscriber line interface 174 is provided. As is known in the art, customer premises devices 112 and 178 are identified by directory numbers and identify devices for call routing functions.

[0015] The common channel signaling system is represented by signal transfer points 140 and 142 interconnected by a signaling link 143. Signal transfer points transmit common channel signaling messages across the public switched telephone network. For simplicity, two signal transfer points
Although only dots are shown, the common channel signaling system includes more signal transfer points. Signal transfer point 140 is interconnected with originating switch 110 by link 145. Signal transfer point 142 is interconnected with destination switch 110 by a signal link 147.
Each signal transfer point is associated with at least one virtual transport server. In the present embodiment,
Signal transfer point 140 is interconnected by link 159 to virtual transport server 150, and signal transfer point 142 is connected by link 151 to virtual transport server 152.

The virtual transport servers 150 and 152 are interconnected by a link 153. Virtual transport server 150 is interconnected with packet circuit gateway 130 by link 155. Virtual transport server 152 is link 1
57 interconnects the packet circuit gateway 132. Each virtual transport server has a processor interconnected with a memory and signal interface. More specifically, virtual transport server 150 includes a processor 180 interconnected by link 183 to memory 182 and interconnected by link 185 to signal interface 184.
Signal interface 184 and memory 182 are linked
87 are interconnected. Similarly, the virtual transport server 152 connects the memory 172 with the link 173.
And a processor 170 interconnected with. The processor connects to the signal interface 176 via the link 175.
Interconnected with The memory 172 and the signal interface 176 are interconnected by a link 179. Signaling interfaces 176 and 184 are associated with signaling links 151 and 159, respectively, to intercept common channel signaling messages transmitted by signaling transfer points. The intercepted messages are stored in memory 172 and memory 1 until the virtual transport server receives a packet data network call connection confirmation as described below.
82.

In one particular embodiment, the virtual transport server establishes a call connection from the originating packet circuit gateway to the terminating packet circuit gateway. For example, in the converged telecommunications system 100, the virtual transport server coordinates the establishment of a voice path (eg, voice path 191) of the packet data network via the packet circuit gateways 130 and 132 and the virtual transport server 152. More specifically, virtual transport server 150 communicates with virtual transport server 152 to establish an audio path from packet circuit gateway 130 to packet circuit gateway 132. In yet another embodiment, a single virtual transport server sets up the audio path or uses multiple virtual transport servers to establish a call connection between the calling party and the called party.

In some embodiments, once the voice path is established, the terminating packet circuit gateway extends the acknowledgment message to the virtual transport server it handles. In this case, the packet circuit gateway 132 extends the acknowledgment message to the virtual transport server 152 via the link 157. This acknowledgment message is relayed to all virtual transport servers involved in the call, including the virtual transport server that first retrieved the common channel signaling call setup message. Upon receipt of the voice path acknowledge message, all virtual transport servers storing the common channel signaling messages associated with the call will send the common channel signaling message to the common channel signaling system so that the call setup can be established using normal procedures. Release the message to the signal transfer point. Stated another way, the voice path of the packet data network is established before the processing of the common channel signaling message is completed. Generally, the packet data network 190 includes an asynchronous transfer mode switch, an Internet protocol switch, or a combination of packet data transfer devices.

FIG. 2 is a flow diagram of the steps performed in the focused telecommunications system 100 according to a first embodiment of the present invention.

The process begins at step 200, where a signaling transfer point (or a node with a common channel signaling system) receives a call setup signaling message from an originating switch. For purposes of illustration, assume that a caller utilizing subscriber premises device 112 makes a call to a callee utilizing subscriber premises device 178. Thus, the originating central office switch 110 sends the call setup common channel signaling message over link 145 to its signaling point 1
Stretch to 40. Next, following step 202, the virtual transport server associated with the signal transfer point receives and stores the common channel signaling message.
In the present embodiment, the virtual transport server 150 searches for a common channel signal message from the signal transfer point 140 and stores it in the memory 182.

In decision step 204, virtual transport server 150 determines whether a predetermined time has elapsed since the common channel signal message was retrieved and stored. If the decision result in decision step 204 is "NO", proceed to step 205, in which the emission of the common channel signaling message is delayed until a predetermined time has elapsed. When the result of the determination in the determination step 204 is “Y
If so, proceeding to step 206, the virtual transport server assumes that a voice path has been established between the calling party and the called party in a different network (eg, the packet data network 190), and Emit the common channel signaling message stored at the signal transfer point that searched for.
Once released, the signaling transfer point establishes call setup using normal processing.

In a first embodiment, a common channel signaling message is delayed in such a manner so that a voice path is established prior to processing the call setup process, and call setup in a different (eg, focused) telecommunications network. I do.

FIG. 3 is a process flow diagram of the steps performed in the focused telecommunications system 100 according to a second embodiment of the present invention. In the second embodiment of the present invention, an intelligent packet circuit gateway capable of performing all functions related to establishing a voice path from an originating central office switch to a destination central office switch in a packet data network is assumed.

The process begins at step 300, where a signal transfer point receives a common channel signaling message from an originating switch. Specifically, the subscriber premises device 112
Follows the above example in which a calling party utilizing. Attempts to initiate a call to a call recipient utilizing subscriber premises equipment 178. Accordingly, in step 300, signal transfer point 140
Receive a common channel signaling message from originating switch 110 via link 145. Next, following step 302, the virtual transport server 150 receives the common channel signaling message from the signal transfer point 140 and stores it in its memory. In step 304, the virtual transport server 150 executes and stores the address rewriting. (That is, the virtual transport server 150 determines the packet network address associated with the common channel signaling message.) Next, in step 306, the virtual transport server 150 The voice route to the call receiver distributed from the destination switch 160 is determined. In this example, the virtual transport server traverses the packet circuit gateway 130, the packet data network 190, and the packet circuit gateway 132 in order for the voice path to reach the call recipient served by the destination switch 160. Judge that it is necessary. Next, in step 308, the virtual transport server 15 is set up so that the voice path 191 is established in the packet data network 190.
Sends a message to all packet circuit gateways affected by 0. In this case, the virtual transport server 150 transmits a message to the packet circuit gateway 130 and the packet circuit gateway 132 via the virtual transport server 152. This allows these packet circuit gateways to communicate between originating central office switch 110 and destination central office switch 1.
The necessary trunk connection is established between the callers 60 and the caller and the callee are connected by the voice path 191 in the packet data network 190.

In decision step 310, virtual transport server 150 determines whether it has received an audio routing confirmation. Decision step 31
If the determination result of 0 is “NO”, step 311
, And the call is automatically interrupted as the predetermined time elapses. The call suspension process is well known in the prior art and will not be described in detail here. Decision step 31
If the result of 0 is "YES", the process proceeds to step 312, in which the virtual transport server 150 transfers the common channel signal message received from the originating switch so that the normal call setup processing is performed by the signal transfer point 140. Release to point 140.

FIG. 4 is a process flow diagram of the steps performed in the focused telecommunications system 100 according to the third embodiment of the present invention. In the third embodiment of the present invention, it is assumed that the virtual transport server is a main part for establishing an audio path.

The process begins at step 400, where the signaling point receives a common channel signaling message from the originating switch. In this embodiment, signaling transfer point 140 receives a common channel signaling message from originating central office switch 110 via signaling link 145. At step 402, virtual transport server 150 receives the common channel signaling message from signal transfer point 140 and stores it in memory 182. Next, following step 404, the virtual transport server 150 performs a packet network address rewrite of the stored common channel signal message and stores the rewrite in its memory. In step 410, the virtual transport server 15
0 establishes an audio path using the packet circuit gateway and the packet data network 190 and provides this information to the packet circuit gateways (ie, packet circuit gateways 130 and 132).

At decision step 412, virtual transport server 150 determines whether a voice path confirmation has been received. Voice path confirmation includes the virtual transport receiving an acknowledgment message from the terminating packet circuit gateway that a voice path has been established via the packet data network. In the present embodiment, the virtual transport server 150 uses the packet data network 1
90 that the audio path 191 has been established.
Wait for acknowledgment from the terminating packet circuit gateway 132 (which handles the destination central office switch 160). If the decision result in the decision step 412 is “NO”, the process proceeds to a step 413, and until the voice route confirmation is received,
The virtual transport server continues to delay the release of the common channel signaling message. If acknowledgment is not received at some point, the call suspension process is initiated. If the result of decision step 412 is “YES”, proceeding to step 414, virtual transport server 150 emits a common channel signaling message to signal transfer point 140 for normal processing.

FIG. 5 is a process flow diagram of the steps performed in the focused telecommunications system 100 according to a fourth embodiment of the present invention. In the fourth embodiment of the present invention, it is assumed that the packet circuit gateway function is incorporated in a central office switch operating on a different network.

The process begins at step 500 where an originating central office switch including a packet circuit gateway function receives a call origination request from one of the subscribers. In this embodiment, the outgoing central office switch 110 receives an outgoing request from the subscriber line 111 using the subscriber premises equipment 112. Next, proceeding to step 502, the originating central office switch determines whether the call origination request has been requested to be completed over a different network. If the determination result of step 502 is “NO”, step 50
Proceeding to 3, the originating central office switch 110 uses normal call processing. In such a case, if the determination result of step 502 is “YES”, step 5
04, the originating central office switch will switch to the common channel signal until the different network terminates its call signal transfer point 140 and the packet data network 190 confirms that the voice path 191 has been established to the destination central office switch 160. Delay transmission of common channel signaling messages to the system.

In decision step 506, originating central office switch 110 determines whether a call processing "complete" message has been received from a different network. In other words, originating central office switch 110 waits for a voice path completion message from packet data network 190. If the determination result of step 506 is “N
If "O", return to step 504 until a call completion message is received. In many embodiments, if a call completion message is not received, a call interruption process is initiated after a predetermined period of time.
If the determination in step 506 is "YES," the process proceeds to step 508, where the originating central office switch emits a common channel signaling message to the common channel signaling system.

Advantageously, the present invention allows for an efficient synchronous call setup process between different networks. In practical conditions, synchronization allows the establishment of a voice path to the packet data network before the processing of the traditional public switched telephone network begins. In this way, adverse effects such as call clipping in a focused telecommunications network are eliminated. Although the embodiments of the present invention have been described in detail, it will be apparent to those skilled in the art that other methods can be used without departing from the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a block diagram of a focused telecommunications system embodying the present invention.

FIG. 2 is a process flow diagram of steps performed in the focused telecommunications system of FIG. 1 according to the first embodiment of the present invention;

FIG. 3 is a process flow diagram of steps performed in the focused telecommunications system of FIG. 2 according to a second embodiment of the present invention;

FIG. 4 is a flow diagram of the steps performed in the focused telecommunications system of FIG. 1, according to a third embodiment of the present invention.

FIG. 5 is a process flow diagram of steps performed in the focused telecommunications system of FIG. 2 according to a fourth embodiment of the present invention;

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor James Philip Lanyon United States 60187 Illinois, Wheaton, Champion Forest Coat 1231 (72) Inventor Sham-von Sue United States 60540 Illinois, Neyperville, Hampton Circle 23 W 267 ( 72) Inventor Shen-Twen Yu United States 60563 Ilynois, Neyperville, Marls Court 1276

Claims (10)

[Claims] 1. A telecommunications system, comprising: a switch interconnected with a first network and a second network; a signaling system interconnected with the switch; and a signaling system interconnected with the signaling system and received by the signaling system. A telecommunications system comprising a virtual transport server (VTS) for receiving and storing messages. 2. The telecommunications system according to claim 1, wherein the first network and the second network are synchronized by delaying a message received by the virtual transport server. 3. A focused telecommunications system according to claim 1, wherein the virtual transport server receives the message from the signal transfer point and stores the message until a voice path is established. Communications system. 4. The focused telecommunications system of claim 3, wherein the virtual transport server emits a message to a signal transfer point based on the confirmation that the voice path has been established. Communications system. 5. A system comprising: a packet circuit gateway for interconnecting with a packet data network; and a virtual transport server (VTS) interconnected with the signaling system and at least one packet circuit gateway. A system wherein a server receives a voice path establishment message from said packet circuit gateway and emits a signaling message to a signaling system. 6. The system according to claim 5, wherein the signaling system is a common channel signaling system. 7. A virtual transport server (VT)
S) has a signal interface, receives CCS messages from the CCS system, and the processor interconnects with the signal interface and the memory;
A virtual transport server for determining when to release a CCS message to a system. 8. The VTS according to claim 7, wherein the VT
A VTS having a link interconnecting S to a packet circuit gateway, wherein a routing request message from the packet circuit gateway is received at the VTS. 9. The VTS according to claim 8, wherein said VTS
A VTS, wherein a CCS message is held until a voice route confirmation message is received from a packet circuit gateway in the TS. 10. The signal transfer point system,
A first link interconnecting the signaling transfer point to a system for generating a CCS message, and a second link interconnecting the signaling transfer point to a system for receiving a CCS message generated by the first system. Wherein the receiving system returns the message to the signaling point after a particular event.