PROCEDURE AND SYSTEM FOR THE TRANSMISSION OF INFORMATION AND SETTING UP OF A TELECOMMUNICATION CONNECTION

Abstract: Procedure and system for optimisation of the route of a telecommunication connection to be set up in a telecommunication system comprising a mobile switching centre (MSC), a service switching point (SSP), a service control point (SCP), a gateway (GW) and a subscriber register (HLR). In the procedure, the service switching point (SSP) is connected to the service control point (SCP) and the gateway (GW) is connected to the service control point (SCP) and to the subscriber register (HLR). The telecommunication connection to be set up is directed via the service switching point (SSP) to the service control point (SCP). A database query is sent from the service control point (SCP) via the gateway (GW) to the subscriber register (HLR). The subscriber register provides routing information, on the basis of which an optimal route to the mobile switching centre under which the B-subscriber is located is determined.

Description: PROCEDURE AND SYSTEM FOR THE TRANSMISSION OF INFORMATION AND SETTING UP OF A TELECOMMUNICATION CONNECTION SCOPE OF THE INVENTION The invention relates to telecommunication technology. In particular, the invention is utilised in the optimisation of the route of a telecommunica- tion connection set up in a mobile communication network. BACKGROUND OF THE INVENTION For a teleoperator, it is important that telecommunication connections be set up in an optimal manner. Optimisation may be based e.g. on the length of the route of the connection or on the network load resulting from the telecommunication connection. The traffic in mobile communication networks is continuously increasing. Therefore, it is particularly important that the load in the mobile communication network should remain as low as possible. One approach to reducing the load in a mobile communication network is to set up the connection to the called subscriber's mobile switching centre via a route as short as possible. PRIOR ART An intelligent network consists of switching, controlling and functional components and a signalling network. A service switching point (SSP) is a modified telephone exchange which analyses the traffic passing through it. When it detects a certain number that meets a triggering criterion, the service switching point SSP sends a service request to a service control point (SCP) . The information required for service control is stored in a service data point (SDP) , where the service control point can obtain the information it needs. Service switching points are connected via signalling channels to service control points, which implement intelligent network services by utilising a service database. A service control point may perform e.g. a number conversion from B-number to C-number by getting the C-number corresponding to a B-number from the service database . The communication protocols used in an intelligent network are rules by which the components • of the intelligent network talk to each other. The protocol defines the interfaces between components as well as the structure of the messages exchanged between them. Intelligent network components communicate with each other using common channel signalling (CCS) . As an ITU-T definition, common channel signalling is known as CCSS No7. For communication between components, an intelligent network uses the services of the INAP (Intelligent Network Application Part) defined by ITU-T. The INAP application part is an intelligent network application protocol used e.g. for communication between a service control point and a service switching point. On the other hand, the MAP application part is a part of the signalling system of a mobile communication network and is used for signalling between the switching centres and registers of the mobile communication network. In the GSM (Global System for Mobile communications) system, a call to be set up is routed as follows. A call setup request is sent from the calling subscriber's (A-subscriber ' s) terminal equipment to a gateway mobile switching centre (GMSC) , which sends a query to the called subscriber's (B-subscriber ' s) home location register (HLR) to determine the mobile switching centre (MSC) under which the B-subscriber ' s terminal device is currently located. The home loca- tion register is a database which contains information including subscriber data, subscriber location data, call control data, short-message services and billing data. Next, the home location register requests the visitor location register (VLR) for a roaming number (MSRN, Mobile Subscriber Roaming Number) and returns the roaming number to the GMSC. The visitor location register is a database in a mobile communication network which contains the information required for the transmission of calls about each mobile subscriber currently located in the area of the network. The roaming number is a temporary identification number which is allocated to a mobile station recorded in the visitor location register and which is used by the mo- bile communication system for the routing of calls addressed to the subscriber. After this, based on the roaming number, the GMSC routes the call originated by the A-subscriber to the mobile switching centre in whose location area (LA) the B-subscriber is located. The B-subscriber ' s mobile switching centre in turn sets up a connection with the B-subscriber ' s terminal device. In the routing procedure described above, the problem is that calls addressed to mobile stations are not automatically routed via the shortest route to the right mobile switching centre but may instead be routed via several switching centres. A solution applied to eliminate this problem is to provide some service nodes (SN) and service control points with a MAP interface, which makes it possible to implement a functionality and service similar to the present in- vention. Such solutions involve the problem that they bind the service to a Gertain base and assume that the service control point or service node is provided with a MAP interface. In the procedure of the invention, the routing of calls addressed to a terminal device is optimised by using an intelligent network service and a special gateway. By means of the gateway, a query is sent from the intelligent network system to a subscriber regis- ter to obtain B-subscriber data and, using said data, the call to be set up is routed directly to the mobile switching centre in whose area the B-subscriber ' s terminal device is located. This also makes it possible to utilise other GSM network services as well. The object of the present invention is to eliminate the drawbacks described above or at least to reduce them significantly. A specific object of the present invention is to disclose a new type of procedure and system for routing a call directly to the mobile switching centre under which the B-subscriber is located. As for the features characteristic of the invention, reference is made to the claims. BRIEF SUMMARY OF THE INVENTION The procedure of the invention is used for the optimisation of the route of a telecommunication connection to be set up. The telecommunication system of the invention comprises a mobile switching centre, a service switching point, a service control point, a gateway and a subscriber register. The service switching point is connected to the service control point . The subscriber register and the service control point are connected to the gateway. The gateway further comprises means for handling a database query, a signalling query, a response to a database - query and a response to a signalling query. In the method of the invention, a telecommuni- cation connection to be set up is directed via the service switching point to the service control point. From the service control point, a database query is performed, which is directed to the gateway. In the gateway, the database query is converted into a sig- nailing query, which is sent to the subscriber register. Based on the data in the subscriber register, a response to the signalling query is defined and sent to the gateway. In the gateway, the response to the signalling query is converted into a response to the database query, on the basis of which the service control point determines an optimal route to the mobile switching centre. In a preferred embodiment of the invention, the response to the signalling query contains routing information, which is used to optimise the route of the telecommunication connection to the mobile switching centre. After this, a connection to the mobile switching centre and further e.g. to the B- subscriber's terminal device is set up. The routing information is e.g. a roaming number, preferably the MSRN (Mobile Subscriber Roaming Number) . In a preferred embodiment of the invention, the gateway is a MAP- INAP gateway, which comprises means for controlling the interface between the serv- ice control point and the database as well as means for controlling the interface between the gateway mobile services switching centre and the subscriber register. The signalling query is preferably an MAP (Mobile Application Part) query and the database query is an SDP (Service Data Point) query. The service control point of the intelligent network is thus enabled to use the subscriber data of the GSM network. In a preferred embodiment of the invention, the subscriber register is the home location register of the GSM system. The invention allows optimal routing to the mobile switching centre under which the B-subscriber is located. If, according to the data in the visitor location register, the subscriber cannot be reached, corresponding information is obtained. If the subscriber has transferred his/her calls to another number using the CFU (Call Forwarding Unconditional) supplementary service, this will also be known and the call can be routed to the forward number. The solution of the invention does not require any changes in the elements of the mobile communication network or in the intelligent network because the invention implements the service " by using a separate MAP-INAP base. LIST OF ILLUSTRATIONS In the following, the invention will be described in detail by the aid of an embodiment example, wherein Fig. 1 presents a system according to the invention, Fig. 2 presents an example of signalling in a preferred embodiment of the procedure of the inven- tion, Fig. 3 presents an example of signalling in a preferred embodiment of the procedure of the invention, and Fig. 4 presents an example of signalling in a preferred embodiment of the procedure of the invention in an error situation. The system illustrated by Fig. 1 comprises a mobile switching centre (MSC) , a service switching point (SSP) , which is connected to a service control point (SCP) . Further, the service control point (SCP) is connected to a gateway (GW) , to which is also connected a subscriber register (HLR) . The signalling diagram presented in Fig. 2 comprises a service control point (SCP) , an MAP-INAP gateway (GW) , a home location register (HLR) and a visitor location register (VLR) . The signalling diagram in Fig. 3 comprises a service control point (SCP) , an MAP-INAP gateway (GW) and a home location register (HLR) . The signalling diagram in Fig. 4 comprises a service control point (SCP) , an MAP-INAP gateway (GW) and a home location register (HLR) . DETAILED DESCRIPTION OF THE INVENTION In an embodiment as illustrated by Fig. 1, a call setup request is sent from the A-subscriber ' s terminal device to the gateway mobile services switching centre. The gate MSC detects the incoming call and directs it further to the service switching point. From the service switching point, the call is directed to the service control point, which performs a database query to obtain routing information. In the procedure of the invention, instead of directing the database query to the service data point, the query is directed to a MAP-INAP gateway, where a conversion from database query into signalling query is performed. The MAP-INAP gateway can be easily implemented e.g. by using a separate service node provided with the required applications for the implementation of the interfaces or by installing the application in an existing intelligent network component, e.g. the service control point. Next, the routing query is sent from the gateway to the B-subscriber ' s home location register, where a response to the signalling query is defined on the basis of the data in the home location register. The signalling query response consists of routing information, preferably a roaming number. The home location register returns the routing information to the gateway, which performs a conversion from signalling query response into database query response. Thus, the routing information is converted into a form understood by the service control point. After this, based on the database query response received, the service control point causes the service switching point to route the call directly to the mobile switching centre under which the B-subscriber ' s terminal device is located. Fig. 2 presents an example of signalling in the procedure of the invention in a situation where the home location register provides a roaming number as a response to a database query. The service control point (SCP) sends a database query (DB-query) to obtain routing information (MSRN) . The database query is directed to a MAP-INAP gateway (GW) , where a conversion from database query into signalling query is performed. Next, the signalling query (Send. Routing. Inf) is sent from the gateway to the B-subscriber ' s home location register (HLR) , where a response to the sig- nailing query is defined on the basis of the data in the home location register. In currently used techniques, the subscriber location data is not always automatically updated from the visitor location register to the home location register. In this case, the home location register (HLR) must first get routing information (Provide. MSRN) from the visitor location register (VLR) . The home location register returns the response to the signalling query (HLR-response) to the gateway, which performs a conversion from signalling query response (HLR-response) to database query re- sponse (DB-response) . The signalling query response (HLR-response) consists of routing information, preferably a roaming number. Fig. 3 presents an example of signalling in a procedure according to the invention in a situation where the B-subscriber has forwarded his/her calls to a C-number. From the service control point (SCP) , a database query (DB-query) is sent to obtain routing information (MSRN) . The database query is directed to the MAP-INAP gateway (GW) , where a conversion from da- tabase query into signalling query (Send. Routing. Inf) is performed. Next, the signalling query is sent from the gateway to the B-subscriber ' s home location register (HLR) , where, based on the data in the home location register, a response to the signalling query is defined. The home location register HLR returns the response to the signalling query (Fwd. To.Number) to the gateway, which performs a conversion from signalling query response to database query response (DB- response) . In the case of the present example, the re- sponse (Fwd. To.Number) to the signalling query is a C- number . Fig. 4 presents an example of signalling in the procedure of the invention in a situation where the B-subscriber can not be reached or there is a mal- function in the telecommunication system. A database query (DB-query) is sent from the service control point (SCP) to obtain routing information. The database query is directed to the MAP-INAP gateway (GW) , where a conversion from database query into signalling query is performed. Next, the signalling query (Send. Routing. Inf) is sent from the gateway to the B- subscriber's home location register (HLR). Based on the information in the- home location register, a response (Routing. Inf .Error) to the signalling query is defined. If the subscriber terminal has been shut off or the subscriber is outside the receiving area, then the response (Routing. Inf .Error) to the signalling query contains data indicating that the subscriber can not be reached. If there is a malfunction in the system, corresponding information can also be given to the service control point in the response (Routing. Inf .Error) to the signalling query. The home location register returns the signalling query response to the gateway, which performs a conversion from signalling query response to database query response (DB- error) . The present application is based on the earlier Finnish application FI 982168 "Procedure and system for the transmission of information and setting up of a telecommunication connection" , which has been filed by the same applicant as the present application and is included here by this reference. The invention is not restricted to the examples of its embodiments described above, but many variations are possible within the scope of the inven- tive idea defined by the claims.

Claims: CLAIMS 1. Procedure for optimisation of the route of a telecommunication connection to be set up in a tele- communication system comprising a mobile switching centre (MSC) , a service switching point (SSP) , a service control point (SCP) , a gateway (GW) and a subscriber register (HLR) , in which procedure the service switching point (SSP) is connected to the service con- trol point (SCP) and the gateway (GW) is connected to the service control point (SCP) and to the subscriber register (HLR) , and in which procedure the telecommunication connection to be set up is directed via the service switching point (SSP) to the service control point (SCP) and a database query is performed from the service control point (SCP) , charact eri sed in that the database query is addressed to the subscriber register (HLR) and, based on the response to the database query, an optimal route to the mobile switching centre is determined. 2. Procedure as defined in claim 1, char ac t eri sed in that the database query is converted in the gateway (GW) into a signalling query; the signalling query is sent to the subscriber register (HLR) ; based on the data in the subscriber register (HLR) , a response to the signalling query is defined; the response to the signalling query is sent to the gateway (GW) ; the response to the signalling query is converted into a response to the database query; the response to the database query is returned to the service control point (SCP) ; routing information corresponding to the optimal telecommunication connection is generated on the basis of the response to the database query; and based on the routing information, a telecommunica- tion connection to the mobile switching centre is set up. 3. Procedure as defined in claim 1 or 2, characteri sed in that the response to the signalling query contains routing information. 4. Procedure as defined in claims 1 - 3, characteri sed in that the routing information consists of a roaming number, preferably the MSRN number (MSRN, Mobile Subscriber Roaming Number) . 5. Procedure as defined in any one of claims 1 - 4, characterised in that the gateway is an MAP-INAP gateway comprising a database interface and a subscriber register interface. 6. Procedure as defined in any one of claims 1 - 5, characterised in that the signalling query is an MAP query (MAP, Mobile Application Part) . 7. Procedure as defined in any one of claims 1 - β, characterised in that the database query is an SDP query (SDP, Service Data Point) . 8. Procedure as defined in any one of claims 1 - 7, characterised in that the subscriber register (HLR) is the home location register. 9. System for optimisation of the route of a telecommunication connection to be set up in a telecommunication system comprising a mobile switching centre (MSC) , a service switching point (SSP) , a service control point (SCP) , a gateway (GW) and a subscriber register (HLR) , in which system the service switching point (SSP) is connected to the service control point (SCP) and the gateway (GW) is connected to the service control point (SCP) and to the subscriber register (HLR) , and in which system the telecommunica- tion connection to be set up is directed via the service switching point (SSP) to the service control point (SCP) , characterised in that the gateway (GW) comprises means for handling a database query, a signalling query, a database query response and a signalling query response.

Inventors: ALA-LUUKKO SAMI, GROEHN TUOMO, PERAE OLLI, SARKKI MIKA, ALA-LUUKKO, SAMI, GROEHN, TUOMO, PERAE, OLLI, SARKKI, MIKA
Applicants: ALA LUUKKO SAMI, GROEHN TUOMO, PERAE OLLI, SARKKI MIKA, SONERA OY, ALA-LUUKKO, SAMI, GROEHN, TUOMO, PERAE, OLLI, SARKKI, MIKA
Application year: 1998
Main classification: H04Q7
IPC codes: H04Q3, H04W8