SYSTEM FOR HANDLING TELEPHONE CALLS

Abstract: A service node forms part of a network which allows service node calls to be managed, without requiring the calls themselves to be routed through the node. Thus, traffic in the network can be reduced, while allowing the provision of enhanced subscriber services. Exchanges within the network allow for the provision of transmission loops, under the control of software of the service node.

Description: SYSTEM FOR HANDLING TELEPHONE CALLS TECHNICAL FIELD OF THE INVENTION The invention relates to telephone switching and, in particular, to telecommunications systems allowing access to enhanced subscriber services . DESCRIPTION OF RELATED ART Enhanced subscriber services, such as freephone calls and charge card calls, are now widely available. Conventionally, all such calls are routed through a respective service node. That is, for example, a local exchange recognises that an incoming call is a freephone call, and routes the call to the relevant service node, which contains a database which relates dialled freephone numbers to physical destination numbers, and which then routes the call onto the intended destination. Moreover, some enhanced subscriber services require interaction between the caller and the service node during call set-up. The ability to offer such services is advantageous for telephone service providers, but the calls themselves are resource intensive. Thus, all freephone calls, say, may be routed through a service node at a particular physical location. This means that each such call generates, on average, at least twice as much traffic as a conventional call. An alternative to this conventional solution is the so-called Intelligent Network architecture, in which local switches are connected to respective Service Switching Points, which are able to access Service Control Points, which each contain a database of enhanced subscriber services . US Patent No. 5,377,186 describes a modification of the Intelligent Network architecture. In such a system, during call set up, signals are sent to an IN Service Control Point, and the call is then established between the local switches, to which the originating and terminating subscribers are connected, through respective Service Switching Points. This IN architecture employs transmission loops as an alternative means of providing separation of call control and the service logic. Moreover, the system described in US Patent No. 5,377,186 has the limitation that it cannot establish temporary connections to network resources, for example for use in prompt and collect type services, in which, for example, a calling subscriber is asked to supply information, either in the form of a voice message or by entering digits, on the basis of which the connection may be made. SUMMARY OF THE INVENTION The present invention seeks to provide a system which allows service providers to deploy enhanced subscriber services in an efficient way, while using existing infrastructure to the largest possible extent. More specifically, while retaining existing service nodes, the system of the present invention seeks to allow the provision of enhanced subscriber services from those service nodes, without requiring the calls to be routed through those nodes. Aspects of the invention relate to the method of handling calls, and to the service node and to the switches themselves. In broad terms, the invention relates to a method of handling telephone calls, in a conventional service node architecture, without requiring upgrading to an Intelligent Networks architecture, in which signalling and call lό ' gic are handled at the service node, while the actual call connection takes place at a local exchange level . In particularly preferred embodiments of the invention, a double loop is set up within the local exchange, allowing the service node to communicate separately with the calling party and the called subscriber. This allows the use of prompt and collect services, in which the service node, for example, requests information from the calling party, and determines, on the basis of that information, how to process the call. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a local switch in accordance with the invention. Figure 2 is a schematic illustration of a second local switch in accordance with the invention. Figure 3 is a schematic illustration of a service node in accordance with the invention. Figure 4 illustrates a first stage in the handling of a call in accordance with the invention. Figure 5 illustrates a second stage in the handling of a call in accordance with the invention. Figure 6 illustrates a third stage in the handling of a call in accordance with the invention. Figure 7 illustrates a fourth stage in the handling of a call in accordance with the invention. Figure 8 is a flow chart describing the handling of a call as illustrated in Figures 4-7. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Figure 1 represents a local exchange in accordance with the invention. Preferably, each local exchange in a network is as described here. However, it is possible to route calls from separate local switches to an exchange as described. As is conventional, the exchange 2 includes a switch 4, which can interconnect subscribers 6, 7 connected thereto. Clearly, in practice, a large number of subscribers will be connected to the exchange. Further, as is conventional, the exchange includes a number of trunk routes 8, 10, of which two are shown in Figure 1, which are connected to different physical transmission ports on the switch 4. In accordance with the invention, the pair of trunks 8, 10 are connected back-to-back with a short cable 12 to form a transmission loop. Thus, these cables are physically connected, but appear to the switch 4 to be two completely separate normal trunks . As described later, this transmission loop can be controlled in order to route a call from one subscriber to a second, while call control signalling is handled elsewhere in the network. As an alternative, the transmission loop may be implemented in software. Figure 2 shows a further development of the exchange shown in Figure 1. In Figure 2 , the exchange 22 includes a switch 24, and two representative subscribers 26, 27 are illustrated. A first transmission loop is formed by linking trunks 28, 30 with a short cable 32, while a second transmission loop is formed by linking trunks 34, 36 by a short cable 38. As before, the transmission loops may be implemented in software . As will be described in more detail later, the availability of two loops allows a calling subscriber and a called subscriber to be handled separately in an enhanced subscriber service call. For example, one party may be put on hold while the other party communicates with the service node . Thus, with two loops, the outgoing half of the first loop can be used to set up a call to the incoming half of the second loop, without involving the application at the service node. Where there is a single loop, the second half of the loop is controlled by the service node to set up the call to the terminating subscriber. Here, the application at the service node may request the connection of a resource to receive messages from, or send messages to, the originating subscriber, using the second half of the loop for connection to the resource (without involving the application directly) . Figure 3 is a schematic illustration of the service node which handles enhanced subscriber service calls in accordance with the invention. The service node 50 is connected to the network 52 through a network interface 54. As in a conventional service node, call management software 56, running on a computer, provides the enhanced subscriber service of the service node, and directs the connections to be made at local exchanges connected to the node, for example as described above with reference to Figure 2. The service node 50 also includes various hardware components 58, of types which are conventionally found in service nodes, relating to the provision of the enhanced subscriber service. For example, the hardware 58 may include means for providing announcements to callers, means for receiving digits input by a subscriber, means for storing and retrieving voice mail messages, and so on. The main difference between the service node 50 in accordance with the invention and a conventional service node is that the transmission and switching hardware in a conventional service node is replaced by connection management software 60. The software 60 can send signals through the network interface 54, and over the network 52 to local exchanges, in order to manipulate the transmission paths in those exchanges, using the C7 signalling protocol, for example. In the examples given above- with reference to Figure 2, it is the connection management software which establishes the required connections. The interaction between the switching node 50 and the local exchange will now be described with reference to Figures 4-7, and the flow chart in Figure 8. The illustrated call is a call made by a calling subscriber to a called subscriber who has a personal number, which means that the call is an enhanced subscriber service call, which is routed through a service node, and can, for example, be routed to different terminating devices at different times, at the option of the called subscriber. Moreover, the called subscriber has access to a call screening service, which means that the calling subscriber is first asked for a voice message, on the basis of which the called subscriber can determine whether or not he wishes to receive the call. In this illustrated embodiment, the calling subscriber 82 and the called subscriber 84 are connected to the same local exchange 86, and the service node 88 is responsible for providing the requested enhanced subscriber service . The service node 88 includes a voice response platform 90, for playing relevant announcements to the parties, and including means for storing and replaying voice messages . Figure 4 illustrates the initiation of the call from the calling subscriber 82. As is conventional, the local exchange recognises, from the dialled number, that th*. call requires to be handled at a service node (step 120 of the flow chart in Figure 8) . The local exchange 86 identifies the required service node 88, and sends the necessary signalling 92 (step 121) . From the dialled number, the service node 88 recognises that the called subscriber has selected a call screening option, which requires that the calling subscriber should record a voice message, on the basis of which the called subscriber can determine whether or not he wishes to take the call (step 122) . The service node 88 therefore directs the establishment of a bearer connection 94 between the calling subscriber 82 and the voice response platform 90 (step 123), for example using a trunk 28 (as shown in Figure 2) forming one half of a transmission loop. Using the other half 30 of the transmission loop, a message is played from the voice response platform to the calling subscriber 82, requesting that the calling subscriber leaves a voice message (step 124) . The message left by the calling subscriber 82 is then stored in the voice response platform 90 (step 125) . The availability of double loops in the local exchange means that, during this phase of the call, the calling subscriber and the called subscriber can be treated entirely separately by the service node. Thus, as shown in Figure 6, the calling subscriber 82 may be put on hold (step 126) , as indicated by reference numeral 96, while the service node establishes a signalling connection 98 to the called subscriber 84, and a bearer connection 100 between the voice response platform 90 and the called subscriber 84 (step 127) . A message may then be played from the voice response platform 90 to the called subscriber 84, indicating that he is about to hear a voice message from the calling subscriber, and indicating what he must do (for example which digits he must enter) if he wishes either to receive the call, or not (step 128) . The message stored by the calling subscriber is then played to the called subscriber (step 129) . In response thereto, the calling subscriber enters the digits (step 130) , indicating whether or not he wishes to receive the call. In the event that the call is to be connected, the service node controls the local exchange 86 to establish a connection directly between the calling subscriber 82 and the called subscriber 84, and the voice platform 90 drops out of the bearer connection altogether. However, signalling connections 92, 98 are maintained (step 131) . With the two parties connected to the same local exchange, it is a simple matter to establish the connection at local exchange level. If the parties are connected to different exchanges, it will probably be more appropriate for the service node to direct the call through a transmission loop at the called party's local exchange. If the called party is on another network (for example in another country) , the service node may direct the call through a second transmission loop on the same as the first, thus using the loops as a means to switch in and out the announcement and digit reception resources . The enhanced subscriber service may therefore be provided from a service node, without requiring the call traffic to be sent to and from the service node.

Claims: CLAIMS 1. A method of handling a telephone call from a first subscriber to a second subscriber, the call requiring management by a service node, the method comprising: establishing a bearer connection between the first subscriber and the second subscriber, the bearer connection being at an exchange level and not passing through the service node ; and establishing signalling connections between the first subscriber and the service node and between the second subscriber and the service node such that the service node controls the call. 2. A method as claimed in claim 1, further comprising, at least during call set-up: establishing a temporary bearer connection between at least one of the first subscriber and the service node, and the second subscriber and the service node. 3. A method of handling a telephone call from a first subscriber to a second subscriber, the call requiring management by a service node, the method comprising: transmitting information from the first subscriber to the service node; establishing a bearer connection between the first subscriber and the service node; establishing a bearer connection between the service node and the second subscriber; transmitting information from the second subscriber to the service node; and establishing a bearer connection between the first subscriber and the second subscriber, without passing through the service node.. 4. A method as claimed in claim 3 , wherein the first and second subscribers are each connected to the service node through a respective local exchange. 5. A method as claimed in claim 3, wherein the first and second subscribers may each be connected to the service node through the same local exchange. 6. A method of handling a telephone call, from a first subscriber to a second subscriber, the first subscriber being connected to a network through a first subscriber's switch, and the second subscriber being connected to the network through a second subscriber's switch, the call requiring user interaction with a service node, the method comprising: recognising at the first subscriber's switch that the call requires handling by with a service node; establishing a signalling connection between the first subscriber and the service node through the first subscriber's switch; recognising at the service node that the call requires user interaction; establishing a bearer connection between the first subscriber and the service node through the first subscriber's switch; sending a message from the service node to the first subscriber; receiving " a message from the first subscriber to the service node; establishing a signalling connection between the second subscriber and the service node through the second subscriber's switch; establishing a bearer connection between the second subscriber and the service node through the second subscriber's switch; sending a message from the service node to the second subscriber; receiving a message from the second subscriber to the service node; establishing a bearer connection between the first subscriber and the second subscriber through the first subscriber's switch and the second subscriber's switch, but not through the service node; and maintaining the signalling connections between the first subscriber and the service node through the first subscriber's switch, and between the second subscriber and the service node through the second subscriber's switch. 7. A method as claimed in claim 6, wherein the first subscriber and the second subscriber share a switch. 8. A method of handling a telephone call, from a first subscriber to a second subscriber, the first subscriber being connected to a network through a first subscriber's switch, and the second subscriber being connected to the network through a second subscriber' s switch, the call requiring user interaction with a service node, the method comprising: recognising at the first subscriber's switch that the call requires handling by a service node; establishing a signalling connection between the first subscriber and the service node through the first subscriber's switch; recognising at the service node that the call requires user interaction; establishing a bearer connection between the first subscriber and the service node through the first subscriber's switch; sending a message from the service node to the first subscriber; receiving a message from the first subscriber to the service node; establishing a signalling connection between the second subscriber and the service node through the second subscriber's switch; establishing a bearer connection between the first subscriber and the second subscriber through the first subscriber's switch and the second subscriber's switch, but not through the service node; and maintaining the signalling connections between the first subscriber and the service node through the first subscriber's switch, and between the second subscriber and the service node through the second subscriber's switch. 9. A service node, for handling enhanced service calls between subscribers connected to a telecommunications network, the service node comprising: a network interface; means for managing calls by providing a particular enhanced service; and means for controlling connections between subscribers at an exchange level. 10. A service node as claimed in claim 9, wherein the means for managing calls is provided in software. 11. A service node as claimed in claim 9 or 10, wherein the means for controlling connections between subscribers is provided in software. 12. A service node as claimed in one of claims 9 to 11, further " comprising hardware means for receiving messages from subscribers. 13. A service node as claimed in claim 12, wherein the hardware means for receiving messages comprises means for recording voice messages. 14. A service node as claimed in claim 12 or 13, wherein the hardware means for receiving messages comprises means for receiving digits supplied by subscribers . 15. A service node as claimed in one of claims 9 to 14, further comprising hardware means for playing messages to subscribers. 16. A service node as claimed in one of claims 9 to 15, wherein the means for controlling connections between subscribers comprises means for sending signals to exchanges, to which the subscribers are connected. 17. A service node as claimed in one of claims 12 to 14, wherein, in response to an incoming enhanced service call from a first subscriber to a second subscriber, the means for managing calls directs the means for controlling connections to establish a connection to the first subscriber and, after receiving a message therefrom, directs the means for controlling connections to establish a connection between the first subscriber and the second subscriber, the connection between the first subscriber and the second subscriber not passing through the service node. 18. A service node, comprising means for providing an enhanced service call between first and second subscribers, and further comprising means for controlling the establishment of a connection between the first and second subscribers at one or more exchanges, such that the connection between the first and second subscribers is not made through the service node . 19. A telecommunications exchange, comprising: means for recognising whether an incoming call requires connection to a service node; a plurality of trunk lines, at least one pair of which are connected back-to-back; and means for routing an incoming call, recognised as requiring connection to a service node, to a trunk line which is connected back-to-back with another line. 20. A telecommunications exchange as claimed in claim 19, comprising at least two pairs of trunk lines, which are connected back-to-back. 21. A telecommunications exchange as claimed in claim 19 or 20, wherein the or each pair of trunk lines are connected back-to-back with short cables. 22. A telecommunications exchange as claimed in claim 19 or 20, comprising software means for connecting the or each pair of trunk lines back-to- back. 23. A telecommunications exchange as claimed in claim 19, comprising hardware means for receiving messages from subscribers, under the control of a service node connected to the exchange by one of said pair of trunk lines. 24. A telecommunications exchange as claimed in claim 20, wherein the hardware means for receiving messages comprises means for recording voice messages. 25. A telecommunications exchange as claimed in claim 20, wherein the hardware means for receiving messages comprises means for receiving digits supplied by subscribers. 26. A telecommunications exchange as claimed in one of claims 23 to 25, further comprising hardware means for playing messages to subscribers, under the control of a service node connected to the exchange by one of said pair of trunk lines. 27. A telephone exchange, having first and second subscribers connected thereto, and having means for connection to a service node, the exchange comprising: means for recognising that an incoming call from the first subscriber to the second subscriber requires connection to the service node; means for establishing a first signalling connection between the first subscriber and the service node ; means allowing a first bearer connection between the first subscriber and the service node, in response to a signal from tne service node; means allowing a second bearer connection between the second subscriber and the service node, in response to a signal from the service node, the second bearer connection being independent of the first bearer connection; means allowing a second signalling connection between the second subscriber and the service node; means for establishing a third bearer connection directly between the first subscriber and the second subscriber, in response to a signal from the service node, and for breaking the first and second bearer connections, while maintaining the first and second signalling connections. 28. A telecommunications network, comprising a plurality of exchanges and at least one service node for handling enhanced service calls between subscribers connected to the network, at least one exchange comprising: means for recognising whether an incoming call requires connection to a service node; a plurality of trunk lines, at least a first and second of which are connected back-to-back with short cables; and means for routing an incoming call, recognised as requiring connection to a service node, to the first trunk line, and the service node comprising: a network interface; means for managing calls by providing a particular enhanced service; and means for controlling connections between subscribers at an exchange level, wherein the service node is able to receive an incoming call from an exchange, on the first trunk line and control the connections within the exchange in order to use the second trunk line connected back-to- back with the first line, firstly for connection back to the calling subscriber during call set-up, and subsequently for connection to the called subscriber. 29. A telecommunications network as claimed in claim 28, wherein the exchange comprises at least two pairs of trunk lines, which are connected back-to-back with short cables, such that the service node can communicate separately with the calling subscriber and the called subscriber during call set-up.

Inventors: DOE STEPHEN RICHARD, DOE, STEPHEN, RICHARD
Applicants: DOE STEPHEN RICHARD, ERICSSON TELEFON AB L M, DOE, STEPHEN, RICHARD, TELEFONAKTIEBOLAGET LM ERICSSON
Application year: 1998
Main classification: H04Q
IPC codes: H04Q3