WO2001048982A1

WO2001048982A1 - Methods and systems for connecting telephony exchanges to packet switched networks using virtual trunks

Info

Publication number: WO2001048982A1
Application number: PCT/US2000/034851
Authority: WO
Inventors: Richard Rogala
Original assignee: Telefonaktiebolaget L.M. Ericsson (Publ.)
Priority date: 1999-12-27
Filing date: 2000-12-21
Publication date: 2001-07-05
Also published as: EP1243104A1; CN1437817A; AU2286801A

Abstract

Methods and system for connecting exchanges to packet switched networks using virtual trunks are disclosed. In accordance with one aspect of the invention, a first node (b) receives an indication from an originating node (401, a) that a call is to be established on an incoming physical device; the first node (b) determines the destination (404, d) for the call and seizes an outgoing virtual device; and the first node (b) indicates to at least one subsequent node (c) having a closer relationship to the destination (404, d) that a call is to be setup and provides the subsequent node (c) with destination information for the call. Another aspect of the invention repeated communication with subsequent nodes (c) closest to the destination node (404, d) until a destination node (404, d) is notified of the call to be established on a physical device associated with the destination node.

Description

METHODS AND SYSTEMS FOR CONNECTING TELEPHONY EXCHANGES TO PACKET SWITCHED NETWORKS USING VIRTUAL TRUNKS

TECHNICAL FIELD OF THE INVENTION The present invention is generally related to telecommunication switching methods and systems. More particularly, the present invention is related to methods and systems for connecting telephony exchanges to packet switched networks using virtual trunks.

BACKGROUND

Information technology and Communication Networks (Networks) provide end users with access to communications and diverse media. Typical Networks include, for example: PSTN (Public Switched Telephone Network) , IP-based (Internet) , ISDN (Integrated Services Digital Network) , and PLMN (Public Land Mobile Network) . Networks provide end users with diverse applications such as: wired and wireless voice, multimedia access/transmission, Internet access, Voice over IP (Internet Protocol), etc. Access to and communication over Networks is accomplished via hardware (e.g., switches, routers, servers, gateway controllers, etc.), and communications protocols (e.g., IP (Internet Protocol) , RLP (Radio Link Protocol) , ATM (Asynchronous Transfer Mode) , GSM (Global System for Mobile Communication), CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), etc.) . In narrow band switches, each call is generally associated to a circuit. Each circuit is connected to the narrow band exchange (e.g., trunks); this requires hardware and switching capabilities dedicated to a trunk. A hierarchy within the narrow band was generally built with access, local, region, transit and international networks. These networks were often built as tree structures, with big transit exchanges that required a lot of capacity. Also the networks were often duplicated for redundancy.

SUMMARY OF THE INVENTION Apparently, current solutions require extensive network planning of the narrow band switches, and extraneous hardware in the narrow band switches are required to build meshed networks. To add hardware, such as a switch, generally requires re-planning of trunks and the network hierarchy.

In accordance with one aspect of the present invention, telephony exchange with virtual trunks (e.g., virtual in the sense that no physical speech channels are needed in the narrow band switches) allow for packet switched communications to be established in cooperation with existing narrow band communication equipment, thereby limiting the need for re-planning and development of narrow band switching networks .

In accordance with a method of the present invention, a first narrow band node receives a indication from an originating narrow band node that a call is to be established on an incoming physical device via a packet switched network; the first node determines the destination for the call and seizes an outgoing virtual device; and the first node indicates to a subsequent node having a closer relationship to the destination device that a packet switched communication is to be setup and provides the second node with destination information for the physical device that is the destination for or will be receiving the packet switched call. The process of transporting information to subsequent nodes is repeated until a node with the closest proximity to, or in association with, the physical device is notified.

In accordance with an aspect of the present invention, a node is provided for connecting telephone exchanges to networks using virtual trunks. The node includes a telephone exchange for providing narrow band signaling capabilities with and between other nodes, and a packet switch network (PSN) interface for providing a connection to a packet switched network for the transmittal and retrieval of communications via the packet switched network. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an illustration of several nodes for facilitating communication and cooperation between packet switched and circuit switched networks; Figure 2 is an illustration of a system having a telephone exchange and switching hardware operating within the narrow band wherein circuit switched related signaling for identifying packet network routed communications may be facilitated within the invention; Figure 3 is an illustration of a system of an embodiment of the invention wherein a narrow band exchange equipment for signaling is incorporated within a node with Packet switched interfacing equipment;

Figure 4 is another illustration of the several nodes of Figure 1 wherein a communication is shown to be initiated A and routed within a packet based network from a first node a to a destination node b wherein the communication is terminated at its destination; and

Figure 5 is an another illustration simplifying the interaction of nodes for communication and facilitation cooperation between a packet-based network and a circuit switched network;

Figure 6 is an illustration of a node for an embodiment of the present invention wherein telephone exchange hardware operates in cooperation with Packet switched networking module to communicate with and a packet switched network and convert packet- and circuit- based communication;

Figure 7 is an illustration of a packet switched networking module for an embodiment of the invention wherein a packet switched to circuit switched converter and packet switched protocol module is utilized to facilitate communication and cooperation between the packet switched network and telephone exchange equipment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides methods and system that combine signaling in the narrow band network to coordinate switching within the packet switch network.

Referring to Figure 1, connections setup in the packet switched network 101 can be meshed, allowing for a packet based communication and/or connection to be setup from its origin A to its destination B without being carried and switched in nodes b and c via, for example, the circuit switched network 102. The present methods and apparatuses operated within a networking environment as depicted in Figure 1, which includes a packet-based network (e.g., packet switched or IP networks) 101, and several nodes (a-d are shown for example) 103 that provide narrow band signaling capabilities, and voice/data conversion and cooperation between the voice and data networks so a communication can be initiated A and terminated B via a packet-based network) . The packet switched 101 and narrow band (circuit switched) 102 networks will be used to describe voice and data capabilities throughout the rest of this description. It should be appreciated by those skilled in the art that packet-based networks include packet switched and IP networks.

Referring to Figure 2, an apparatus 201 having a telephone exchange 202 and switching hardware 203 operating within the narrow band wherein circuit switched related signaling 204 for identifying packet network routed communications 205 is illustrated. Such hardware may be facilitated within the invention for purposes of providing voice layer signaling 204 that will identify the setup of a PSN based communication to a targeted/destination device. A narrow band switch 203 generally includes software for handling the routing of circuit switched calls. Interfaces to the packet switched network can be adapted to the switch 203 for handling packet-based communication, as will be discussed in more detail.

The switch 203 under normal circuit switched applications generally connects telephony devices on the network. When a call is placed, ISUP signaling 204 is used to coordinate call placement. Referring to Figure 3, equipment associated with the narrow band equipment 201 in Figure 1 is utilized as part of a node 300 wherein a narrow band exchange 301 and packet switch networking module 302 cooperate to facilitate the placement of a packet-based 303 communication 304. The Narrow band exchange 301 provides ISUP signaling 305 between nodes, and the packet switch networking module 302 facilitates cooperation between narrow band 305 and packet switched networks 303 at the initiation and termination of the communication 304. The node 300 represents the virtual device of the present invention that facilitates the connection of telephony exchanges to packet networks and cooperation between packet and voice based networks . Referring to Figure 4, when the packet switched connection is to be setup A, the end address B for the connection needs to be determined. With the present invention, the packet switched address (and a identification of the connection) may be forwarded from an initiating node 401 (also shown as and referred to in the following sequence of actions as node "a") to the remote node 404 (example shown as node "d") through several intervening nodes, nl through n2 (also referred to as "b" and "c") . Information is transmitted via ISUP 405 in the narrow band with circuit switched networking hardware. A connection is setup between node a and d with packet switched signaling 407 (including the identity of the connection) via node 401. All nodes may be traversed back so that node 401 receives nodes 404 ' s, address. Connection coordination is needed so that it is known if a node breaks the connection or changes the connection, and if a protocol between the nodes are needed.

The following sequence of actions may occur during connection: 1) Node "a" receives a indication that a call is to be established on incoming physical device. Node "a" finds the destination and selects an outgoing virtual device. Node "a" does not need to switch the call since a Virtual device is involved. Node "a" indicates to node "b" that a call is to be setup.

2) Node "b" receives the indication that a call is to be established on a virtual device. Node "b" finds the destination and selects an outgoing virtual device. No switching is needed since a virtual device is involved. Node "b" indicates to node "c" that a call is to be setup.

3) Same actions are repeated for node "c".

4) Node "d" receives a indication on a virtual device and finds the outgoing device, this device is a physical device. Now the packet switched connection needs to be setup. Node "d" connects with Node a via the packet switched network in order to begin retrieving the communication .

Each node in Figure 4 may be representative of a narrow band exchange. Trunks are used to get place traffic into the exchanges. The signaling protocol and the trunks are separated so that they can have a separate network for the signaling using a narrow band signaling protocol (e.g., which is usually the ISUP, ISDN User Protocol).

The destination exchange within Figure 4 would be Node "d" and Node "a" is the initializing exchange. In- between the initial exchange "a" and the destination "d" exchange might be several other exchanges that the call needs to be set up through. Additional signaling like ISUP would generally be used to carry out the signaling throughout all exchanges. Between node "a" and node "b", there will generally be physical connections operating on different layers. The signaling layer, which is the ISUP, and then the actual layer where the connection is made. Routing tables are used at each node to identify whether it is the terminating node, or to further route the signaling information towards the terminating node. Although the signaling layer is used to coordinate the connection from A to B through the nodes (a-d) , it is beneficial for the actual connection will occur through the packet switch network.

The conditions and/or activities of the nodes may be further summarized as follows, wherein: 1) Node a: physical device to virtual device. No action with PSN.

2) Node b: Virtual device to virtual device. No action with PSN.

3) Node c: Virtual device to virtual device. No action with PSN.

4) Node d: Virtual device to physical device. Send connect request with own ATM address + connection id to node c.

5) Node c: receives a connect request and check if the connection is operated between the virtual channels.

If operated send request to node b.

6) Node b same as in 5) .

7) Node a receives a connect request and checks the if the virtual connection is operated. In this case it is operated to a physical device and the packet-switched (e.g., ATM) setup can be sent to node d.

8) Node d receives a ATM connect request with the connection id.

9) Node d acknowledges the ATM connection and the packet-switched network connection is established. Each node has identifiers for virtual channels in the narrow band protocol. Identifying information is provided to exchanges through the narrow band signaling to route the call to the right destination. Nodes go through routing analyses, to identify which trunk should be used to approach the destination. So when a is looking for d, it goes through the virtual network (e.g., through ISUP signaling) and finds the destination B. Node "d" will be responsible for going back through the packet switch network and picking up the call that it's waiting for at a, given nodes a's information. Node d connects with Node a through the packet switch network, and find the call that's waiting for B. Addressing such as ATM or IP are utilized to identify the communication source and/or destination Initial signaling will have to carry with it addressing information for purposes of setting up the call through the packet-based network.

Referring to Figure 5, a further illustration simplifying the interaction 503 of nodes a-d for communication and facilitating cooperation between a packet-based network 501 and a circuit switched network 502 is illustrated. Nodes "a" through "d" of the example are shown connected to each other for signaling and connection coordination purposes, while only nodes "a" and "d" are shown connected to an ATM network 501 for communication delivery retrieval. Referring to Figure 6, an illustration of a node 601 for an embodiment of the present invention wherein telephone exchange hardware 602 operates in cooperation with Packet switched networking module 603 to communicate with and a packet switched network 604 and convert packet- and circuit-based communication is shown in Figure 6. The telephone exchange 602 coordinates ISUP 605 between other nodes. The packet switched networking module 603 facilitates cooperation between networks. The packet switch networking module 603 communicates with the packet switch network and converts between packet transport protocols and voice transport.

Referring to Figure 7, further an illustration of the packet switched networking module 603 is shown wherein a packet switched to circuit switched converter 701 and packet switched protocol module 702 is utilized to facilitate communication and cooperation between the packet switched network 703 and telephone exchange equipment 704. There are several benefits to utilizing the methods and systems taught. First, Lower equipment and network costs are realized where less long distance switching is required for voice communications. Furthermore, as exchange requirements grow, users experience capacity problems to handle desired services. The invention makes it possible to reduce the hardware in the narrow band switches. It allows for simple provisioning, planing and expansion of narrow band trunks carried over a packet switched network. Also it allows for a simple method to add narrow band switches to the network so that call capacity can be increased or redundancy be achieved; and it is now simple to add switches to a network so that more access points can be spread throughout the network. The following advantages are realized through the present invention when compared to circuit switched networks:

1) Virtual trunks can be overdimensioned, simpler planning for the trunks.

2) No need for speech devices in the narrow band switch.

3) Narrow band Network can be meshed or planned in a flexible way since there is no extra speech devices needed for a fully meshed network.

4) Call control capacity (narrow band switches) can be added without a huge network replaning.

5) Redundancy can be achieved easily since the network can be meshed.

Claims

CLAIMS : 1. A method for coordinating transmission of a voice communication through packet switched networks via nodes represented by narrow band telephone exchanges in associating with packet switched networks, comprising the steps of: a) a first node receives a indication from an originating node that a voice communication is to be established on an incoming physical device; b) the first node determines the destination for the communication and selects an outgoing virtual device; and c) the first node indicates to a second node having a closer relationship to a destination node that a call is to be setup over the packet switched network and provides the second node with destination information for the call

2. The method of claim 1, wherein steps a through c are repeated for subsequent nodes until a destination node is notified of the call to be established on a physical device in communication with the packet switched network and associated with the destination node.

3. The method of claim 2, wherein once the destination node is notified of the call to be established, a packet switched connection is established on a circuit switched network between the incoming physical device and the physical device associated with the destination node.

4. The method of claim 1 wherein the indication received by the first node and provided the second node is via narrow band protocols.

5. The method of claim 4 wherein the narrow band protocol is ISDN user protocol.

6. A method of using narrow band network signaling to coordinate voice communication transport between nodes associated with a packet-switched network, comprising: a first node receives an indication from an originating node that a voice communication call is to be established on a physical device associated with a destination node and the packet-switched network; and the first node determines the destination for the call and selects an outgoing virtual device to send notification of the identity of the communication and its destination to a subsequent node closer to the destination node.

7. The method of claim 6, wherein the destination node, after receiving identifying information for the voice communication, selects an outgoing physical device in communication with the packet switched network and prepared for receipt of the communication.

8. The method of claim 6 wherein the steps of selecting subsequent nodes are repeated until the destination node is selected.

9. The method of claim 8 wherein the destination node receives indication that a voice communication from an originating node will be transmitted to the destination node over the packet switched network and is provided identifying information for the communication.

10. The method of claim 9, wherein the destination node coordinates with the originating node to receive the communication through a packet switch network.

11. A node for connecting telephone exchanges to networks using virtual trunks, comprising: a telephone exchange for providing narrow band signaling capabilities with and between other nodes; and a packet switch network (PSN) interface for providing a connection to a packet switched network for the transmittal and retrieval of communications via the packet switched network.

12. The node of claim 11, said packet switch network interface further comprising a converter for converting packetized voice to unpacketized analog voice and unpacketized analog voice to packetized voice.

13. The node of claim 11, said packet switch network interface further comprising a converter for converting packetized voice to unpacketized digital voice, and unpacketized digital voice to packetized voice.

14. The node of claim 11, wherein the narrow band signaling uses a narrow band signaling protocol.

15. The node of claim 11, wherein the narrow band protocol is the ISDN user protocol

16. The node of claim 11, wherein said node is a telephone exchange modified to provide packet switched networking capabilities.