WO2002080491A1

WO2002080491A1 - Mechanism for managing mobility in telecommunication networks

Info

Publication number: WO2002080491A1
Application number: PCT/FI2002/000268
Authority: WO
Inventors: Ilpo Paltemaa
Original assignee: Nokia Corporation
Priority date: 2001-03-30
Filing date: 2002-03-27
Publication date: 2002-10-10
Also published as: FI20010665A; FI112770B; EP1386468A1

Abstract

The invention relates to a mechanism in a telecommunication network comprising transferring messages between a domain name server (DNS), an address server (DHCP) and serving nodes (DXT 1, DXT 2, DXT 3) via an IP network; allocating from the domain name server (DNS) at least one identifier to a subscriber (MS A, MS B) for indicating the subscriber (MS A, MS B); allocating from the address server (DHCP) an IP address to the subscriber (MS A, MS B) when the subscriber (MS A, MS B) for the first time registers in one of the serving network nodes (DXT 1, DXT 2, DXT 3) in a new IP subnetwork; and updating the new IP address on the domain name server (DNS), wherefrom the serving network nodes (DXT 1, DXT 2, DXT 3) are able to ask for the IP address of the subscriber (MS A, MS B) by means of said at least one name identifier reserved for the subscriber.

Description

MECHANISM FOR MANAGING MOBILITY IN TELECOMMUNICATION NETWORKS

BACKGROUND OF THE INVENTION

[0001] The invention relates to telecommunications technology, and particularly to mechanisms that support mobility management in telecommunication networks.

[0002] In telecommunication networks, the increasing number of subscribers, the decreasing cell sizes and the increasing versatility of services multiply both the need for updating subscriber databases and the number of location information inquiries. Location information is the most rapidly changing type of subscriber information. In addition, as network sizes increase, subscriber mobility sets requirements on storing the subscriber and location information in a centralized subscriber database called a Home Location Register (HLR) and in a Visitor Location Register (VLR) element of an exchange carry- ing out service control. New, increasing amounts of information require more powerful processing and disk back-up technology that cannot be provided by the existing exchange technologies.

BRIEF DESCRIPTION OF THE INVENTION

[0003] An object of the invention is thus to provide a new mecha- nism for mobility management in telecommunication networks.

[0004] The object of the invention is achieved by a method and a system characterized by what is disclosed in the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.

[0005] The invention is based on the idea that a telecommunication network is provided with a packet network domain name server and a packet network address server for managing location information on radio subscribers. When a subscriber registers as a user of a network service, an IP address is reserved for the subscriber from the address server. In connection with the registration, one or more name identifiers have been or are reserved from the domain name server for indicating the subscriber. The new IP address is updated on the domain name server, wherefrom other network nodes may now ask for the subscriber's IP address by means of the name identifier(s) reserved for the subscriber. The domain name server thus enables the subscriber to be called by means of several names even if the IP address changes when the location of the subscriber changes sufficiently within the network. [0006] The invention enables a simple way of introducing additional capacity for location information management since no information has to be updated in a centralized subscriber register when a subscriber registers in a network. The centralized subscriber register may, however, be used for check- ing whether or not the subscriber is authorized to use the network's services. An advantage of the invention is that it enables standard IP protocols and devices to be utilized in the implementation of location management.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The invention is now described in closer detail in connection with the preferred embodiments and with reference to the accompanying drawings, in which

[0008] Figure 1 shows storing subscriber information and location information,

[0009] Figure 2 shows updating subscriber location information, [0010] Figure 3 shows call control to subscriber B,

[0011] Figure 4 shows returning a subscriber's call to a new location register,

[0012] Figure 5 shows operator-controlled updating of subscriber information, and [0013] Figure 6 shows dispatcher-controlled updating of group information.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Although in the following the invention and its preferred embodiments will be described in connection with TETRA (TErrestrial Trunked RAdio) and IP (Internet Protocol) systems, the basic principles of the invention can be implemented in any telecommunication system using at least one subscriber database for subscriber mobility management. These telecommunication systems include Private Mobile Radios (PMR) and Public Access Mobile Radios (PAMR), Public Land Mobile Networks (PLMN) and/or fixed Public Switched Telephone Networks (PSTN), for example.

[0015] A TETRA system is a digital telecommunication system, which is developed for public safety and security, public trunking operators and utilities and industry. A typical TETRA system basic network architecture comprises Digital Exchanges for TETRA (DXT), to which TETRA Base Stations (TBS) are connected. The TETRA system can use a decentralised subscriber database structure, i.e. the system may comprise a home location register HLR and/or a Home Database (HDB), which comprises permanent information on a subscriber and/or a group in the subscribers' home network, and a visitor location register VLR and/or a Visitor Database (VDB), which comprises tem- porary information on a subscriber and/or a group visiting a network. Each DXT element may be accompanied by a VLRΛ/DB element. Some exchanges DXT serve as gateway mobile services switching centres or gateways to other telecommunication networks.

[0016] However, since the invention does not relate to the operation and/or structure of the TETRA system per se, these will only be described so as to alleviate the understanding of the invention. For a more detailed description of the TETRA system, reference is made to the TETRA specifications issued by the European Telecommunications Standards Institute (ETSI), available for instance at www.etsi.org. [0017] An IP system refers to a telecommunication network of the

Internet type wherein a message is transmitted from a sender to a receiver by means of an IP protocol. In such networks, the IP protocol is the actual network protocol, which is responsible for routing an IP message including an address from a source to a destination. A particular advantage of a TCP/IP proto- col (Transmission Control Protocol/Internet Protocol), which serves as the data transfer protocol of the Internet, is its independence from different hardware and software architectures.

[0018] In the Internet networks, data is transferred as packet- switched data transfer. In the packet-switched data transfer, data is divided into packets wherein each packet, in addition to information payload, comprises a source address and a destination address. Each packet is routed through a packet-switched network individually on the basis of the address information. This, then, enables data packets relating to the same communication to travel via different routes and by different delays from the source to the destination, depending on the load of the network.

[0019] Different configurations exist for the way in which a TETRA system exchange DXT may be connected to an IP system telecommunication network. In a configuration, each DXT unit can be provided with a direct "exit" of its own through an adjacent router in order to forward IP packets from the TETRA network to the Internet, or vice versa. A router is herein used to refer to a device and/or software in a telecommunication network node, a host, capa- ble of directing, on the basis of an address, the information to be transferred in the network to another, possibly different network. In another configuration, only one or few of the DXT units, which can be called a gateway DXT, is/are connected to an Internet router while the rest of the DXT elements are con- nected to the Internet through these gateway DXT elements. Each exchange DXT may constitute its own IP subnetwork that has its own local IP address space, as shown in the example of Figure 1. Similarly, an IP subnetwork may comprise two or more exchanges DXT, which thus share a common local address space. An IP packet comprising an IP address that belongs to the local address space of an IP subnetwork will be routed to the particular subnetwork. [0020] Figure 1 shows storing TETRA system subscriber information and location information according to the invention and the preferred embodiments thereof. A subscriber database resides in an HLR. All changes in the information, as well as a user's first registration carried out by an operator Operator, primarily take place in the HLR. Typically, the information comprises different numbers and identifiers of a terminal, calling and receiving rights of a subscriber and supplementary services activated for a user. In contrast to the prior art solutions, however, the subscriber information in the home location register according to the system of the invention does not contain location in- formation.

[0021] Depending on the size, number of subscribers and service types of a network, there may be several home location registers HLR. These registers can share the load on the basis of the number of subscribers, service types or another distribution manner optimising information management. In addition to the home location registers HLR, a large network may comprise visitor location registers VLR. An exchange and a VLR may also be combined into one network element.

[0022] In a preferred embodiment of the invention, the mobility management in a telecommunication network comprises, in addition to the above-mentioned elements, an address server DHCP (Dynamic Host Configuration Protocol), which is responsible for allocating IP addresses to subscribers at the exchanges' request. Subscriber location information is updated on the address server DHCP. The network may also comprise a DNS (Domain Name Server) to enable a terminal, such as a mobile station MS, to be paged using several names even if the IP address changes as the subscriber's location changes. The DNS carries out name-address conversions. A domain name server DNS and an address server DHCP may be combined into one element. [0023] All the above-mentioned elements are preferably combined with each other by means of a packet-switched network supporting the IP pro- tocol and IP packet routing based on an IP address; such a network is herein generally called an IP network. An IP network may, for instance, be an operator's intranet, a local area network LAN or even the Internet. The transfer of messages associated with the mobility management according to the invention is carried out through an IP network. In contrast, the actual calls may be estab- lished either as circuit-switched calls (e.g. a TETRA call) or as packet-switched calls (e.g. a Voice over Internet Protocol (VoIP) call).

[0024] When a radio subscriber registers as a user of a network service, an IP address is reserved for the subscriber station from an address server DHCP. In connection with the registration, for example, some identifiers, such as an MSISDN (Mobile Station ISDN Number), ITSI (International TETRA Subscriber Identity), abbreviated number and a name, may have been or are reserved from the domain name server DNS for indicating the subscriber. The new IP address is updated on the domain name server DNS to enable future identification of the subscriber by means of the identifiers reserved for the sub- scriber, as well as the IP address. In other words, an identifier or identifiers may be permanently added to the domain name server when the subscriber is being created and/or temporarily in connection with registration, for example. This could be the case when, for example, an identifier can be transmitted from a sender in a message requesting for registration. Alternatively, an HLR ele- ment, for example, may be asked for an identifier/identifiers when, for instance, the domain name server temporarily stores the identifiers.

[0025] Figure 2 shows updating subscriber location information. When a subscriber moves into the area of a new location exchange DXT_1 in step 1 , the exchange DXT_1 , in steps 2 and 3, may first check from the sub- scriber's home location register HLR whether or not the subscriber is authorized to use the services of the network. The exchange DXT_1 does not, however, give the subscriber location information to the home location register HLR, as is the case in the conventional systems. After potential authentication and identification request comparison, in step 6, the exchange may establish an IP connection to the old location exchange DXT_2 by means of the subscriber's identifier. During connection setup, in steps 4 and 5, the domain name server DNS may have been asked for the IP address corresponding with the user's name, and the IP network may route messages to the old exchange DXT_2 on the basis of the old IP address. The exchange may use a message for providing the information on the new location. The old location exchange DXT_2 may remove the subscriber information from its register and, in step 7, it may or may not send information on the subscriber, such as the groups to which the subscriber belongs, for example, to the new exchange DXT_1. The connection to the old location exchange DXT_2 can thus be established entirely by means of the IP network elements, without loading the home location register. Finally, the location exchange DXT_1 may ask the address server DHCP for a new address for the subscriber MS_1. If the IP subnetwork has changed, the address server DHCP may give the subscriber a new address and update this on the domain name server. The information on the subscriber's previous location exchange DXT_2 may now also be removed. The new VLR information may also be updated in the HLR.

[0026] A new IP address can always be reserved for the subscriber from a location exchange subnetwork, after which the IP network routers are automatically able to deliver the data packets. An address can be reserved using the DHCP protocol, which is the Internet standard. The address server DHCP based on the DHCP protocol issues the address. Furthermore, a necessary number of identifiers are created for the subscriber in the standard Internet domain name server DNS. This element maintains information on the IP addresses corresponding with the names.

[0027] An example of a practical identifier is ISSI7000200, which can be created from the selection of a network or a caller when the subscriber registers. Similarly, identifiers can be created in all those manners in which a subscriber has to be accessible in a network, such as MSISDN0405384208, FSSN65977 and TAPIOLA00230. Identifiers can also be created in a home location register in a similar manner. If, for example, one HLR is the home lo- cation register of all ISSI (Individual Short Subscriber Identity) numbers starting with 6 and 7, two names, HLR6 and HLR7, may be reserved for the home location register. In such a case, connections are established from the exchanges and operator/dispatcher systems simply by using the name.

[0028] Figure 3 shows call control to subscriber B. Since in the case according to Figure 3 subscriber A makes a call to another mobile subscriber, the exchange DXT_1 of subscriber A is able to create an identifier (IP host name) from the number selected by subscriber A.

[0029] The exchange DXT_1 may start establishing an IP connection to the subscriber, and in step 2, in connection with connection setup, the domain name server may be asked for the IP address corresponding with the identifier of subscriber B. In step 3, on the basis of the address returned, the IP network is able to route messages to the location exchange DXT_2 of subscriber B in step 4. The messages may be routed via one or more gateway elements, for example. Next, in step 5, the call can be set up to an exchange DXT 3 of subscriber B through a central network. The subscribers' rights can be checked e.g. on the basis of the subscriber information copied into a local area register VLR_3.

[0030] In the system of the invention, a call can thus be established without loading the subscribers' home location registers HLR. Messages are routed to a correct exchange automatically by means of the IP network routers. A call from subscriber A to subscriber B can be established either as a circuit- switched call (e.g. a TETRA call) or as a packet-switched call (e.g. a Voice over Internet Protocol (VoIP) call).

[0031] Figure 4 shows returning a subscriber's call to a new location exchange. When the location of the subscriber changes during an ongoing call, call return may be requested for in the new location exchange DXT_1.

[0032] First, in steps 2 and 3, the exchange DXT_1 may check from the subscriber's home location register HLR whether or not the subscriber is authorized to use the services of the network. Next, in step 6, the exchange DXT_1 may establish an IP connection to the old location exchange DXT 2 by means of the subscriber's identifier. Prior to the connection setup, in step 4 and 5, the domain name server DNS may or may not have been asked for the IP address corresponding with the subscriber's name. The IP network may route messages to the old location exchange DXT_2 on the basis of the IP ad- dress. The exchange DXT_1 may use a message to provide the subscriber's new location and possibly to ask for call return as well. The old location exchange DXT_2 may remove the information on the subscriber from its register and, in step 7, possibly send information on the subscriber, such as the groups the subscriber belongs to and information on the ongoing call, such as informa- tion on a second subscriber to the call, to the new exchange DXT_1. Next, in steps 8 and 9, the location exchange DXT_1 may ask the address server DHCP for a new address for the subscriber. If the IP subnetwork has changed, the address server DHCP may give the subscriber a new address and update the information on the domain name server.

[0033] In step 10, the exchange DXT_1 may establish an IP con- nection to the location exchange DXT_3 of the other party to the call on the basis of the received IP address. During connection setup, the domain name server can be asked for the IP address corresponding with the subscriber's name, and the IP network routes the messages to the old location exchange DXT_2 on the basis of the IP address. Next, the call may be connected to the new location exchange DXT_1 through the central network.

[0034] In the system of the invention, a call can thus be returned without loading the subscribers' home location registers. Messages are routed to a correct exchange automatically by means of the IP network routers. On the other hand, there is no need for tunnelling of the IP packets using e.g. mo- bile IP technology, which loads the IP network, because a new address for the subscriber is requested in the new location exchange, and the other party to the call is informed of this.

[0035] Figure 5 shows operator-controlled updating of subscriber information. The changes in the subscriber information carried out by the opera- tor can be made in the home location register HLR of the subscriber information in step 1. In step 4, the HLR is able to establish an IP connection to the local area register VLR of the subscriber's location exchange by means of the subscriber's identifier. During connection setup, in steps 2 and 3, the domain name server DNS can be asked for the IP address corresponding with the subscriber's name, and the IP network may route the messages to the location exchange and the local area register VLR on the basis of the IP address. The local area register VLR can acknowledge the changes to the home location register HLR in step 5.

[0036] When a new subscriber is being created, the home location register HLR does not have to convey the information to the local area register VLR. Instead, the subscriber's names can be created on the domain name server DNS.

[0037] Figure 6 shows dispatcher-controlled updating of group information. When the dispatcher changes the group information in step 1 , the changes can be carried out directly in the home location register HLR. In step 4, the home location register may establish an IP connection to the local area register VLR of the subscriber's location exchange by means of the subscriber's identifier. During connection setup, in step 2 and 3, the domain name server DNS can be asked for the IP address corresponding with the subscriber's name, and the IP network may route the messages to the location exchange on the basis of the IP address. The local area register VLR can acknowledge the changes to the home location register HLR in step 5.

[0038] The invention enables IP technology to applied to storing and inquiring location information. In this manner, most of the update load of the centralized subscriber register, i.e. location updates, for example, may be turned into the responsibility of the elements using the IP technology. The IP technology has introduced powerful equipment and standardized development and application tools. In accordance with the invention, an IP network domain name server DNS and an address server DHCP can be arranged in a cellular radio network in order to manage radio subscribers' location information, as described above.

[0039] When a subscriber registers in a network according to the invention, no information has to be updated in the centralized subscriber register HLR. In the conventional systems, subscriber-specific location information is maintained in the home location register and information on the subscriber's new location is also updated in the particular register. The invention thus enables the advantage to be achieved that the capacity and/or number of home location registers does not have to be increased in the network, as is the case in the prior art solutions, in the GSM system, for example. Consequently, the invention provides an easy way of increasing the capacity for managing loca- tion information.

[0040] In addition to the above-mentioned examples, also other network, tele- and/or supplementary services of telecommunication systems can be used by means of the invention and the preferred embodiments thereof. [0041] It is obvious to one skilled in the art that as technology advances, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not restricted to the above- described examples but they may vary within the scope of the claims.

Claims

1. A method for managing mobility in a telecommunication network comprising subscribers (MS_A, MS_B), serving network nodes (DXT_1, DXT_2, DXT_3) and at least one home location register (HLR) wherein sub- scriber information on the subscribers (MS_A, MS_B) is stored permanently, characterized by managing the subscriber information on the subscribers (MS_A, MS_B) by means of an IP domain name server (DNS) and an IP address server (DHCP), transferring messages between the domain name server (DNS), the address server (DHCP) and said serving nodes (DXT_1, DXT 2, DXT_3) via an IP network, reserving at least one identifier for the subscriber (MS_A, MS_B) from the domain name server (DNS) for indicating the subscriber (MS_A, MS_B), allocating an IP address from the address server (DHCP) to the subscriber (MS_A, MS_B) when the subscriber (MS_A, MS_B) for the first time registers in any one of the serving network nodes (DXT_1, DXT_2, DXT_3) in a new IP subnetwork, updating the new IP address on the domain name server (DNS), wherefrom the serving network nodes (DXT_1 , DXT_2, DXT_3) are able to ask for the IP address of the subscriber (MS_A, MS_B) by means of said at least one name identifier reserved for the subscriber.

2. A method as claimed in claim 1, characterized by reserv- ing said at least one identifier on the domain name server (DNS) when the subscriber (MS_A, MS_B) is being created.

3. A method as claimed in claim ^characterized by generating said at least one identifier on the domain name server (DNS) when the subscriber (MS_A, MS_B) registers in the network.

4. A method as claimed in any one of claims 1 to 3, characterize d in that updating the location information on the subscriber (MS_A, MS_B) comprises the steps of when the subscriber (MS_A, MS_B) changes the serving node (DXT , DXT_2, DXT_3), a new serving node (DXT_1, DXT_2, DXT_3) check- ing the rights of the subscriber (MS_A, MS_B) by making an inquiry to the home location register (HLR) of the subscriber, the new serving node (DXT_1 , DXT 2, DXT_3) asking the domain name server (DNS) for the IP address of the subscriber (MS_A, MS_B) on the basis of the name identifier reserved for the subscriber (MS_A, MS_B), the domain name server (DNS) sending the IP address corresponding with the name identifier to the new node (DXT_1 , DXT_2, DXT_3), the new serving node (DXT_1 , DXT_2, DXT_3) sending the information about the new location of the subscriber (MS_A, MS_B) to the old serv- ing node (DXT_1 , DXT_2, DXT_3) by means of said IP address, the old serving node (DXT_1 , DXT_2, DXT_3) removing the information on the subscriber (MS_A, MS_B) from its register, the new serving node (DXT_1 , DXT_2, DXT_3) asking the address server (DHCP) for an IP address for said name identifier, the address server (DHCP) allocating the new IP address to the subscriber (MS_A, MS_B) and updating it on the domain name server (DNS) if the IP subnetwork has changed, or the address server (DHCP) retaining the old address of the subscriber (MS_A, MS_B) if the IP subnetwork has not changed, the address server (DHCP) giving the IP address to the new serving node (DXT_1 , DXT_2, DXT_3).

5. A method as claimed in any one of claims 1 to 4, c h a r a c t e r i z e d in that routing a call from a calling subscriber (MS_A, MS_B) to a called subscriber (MS_A, MS_B) comprises the steps of the calling subscriber (MS_A, MS_B) selecting the called subscriber

(MS_A, MS_B) by means of a subscriber identifier, such as a telephone number, a first node (DXT_1 , DXT_2, DXT_3) serving the calling subscriber (MS_A, MS_B) inferring a name identifier from the selected subscriber identi- fier, the first node (DXT , DXT_2, DXT_3) asking the domain name server (DNS) for the IP address of the called subscriber (MS_A, MS_B) by means of said name identifier inferred, the domain name server (DNS) sending the IP address correspond- ing with the name identifier to the first node (DXT_1 , DXT_2, DXT_3), the first node (DXT_1 , DXT_2, DXT_3) routing the call to the node serving the called subscriber (MS_A, MS_B) by means of said IP address.

6. A method as claimed in any one of claims 1 to 5, c h a r a c t e r i z e d in that returning the subscriber's (MS_A, MS_B) call in the new serving node (DXT_1 , DXT_2, DXT_3) comprises the steps of the subscriber (MS_A, MS_B) changing the serving node (DXT_1 , DXT_2, DXT_3) and asking the new node (DXT_1 , DXT_2, DXT_3) for call return, the new node (DXT_1 , DXT_2, DXT_3) checking the subscriber's (MS_A, MS_B) right to use the services of the telecommunication network from the home location register (HLR) of the subscriber (MS_A, MS_B), the new node (DXT_1 , DXT_2, DXT_3) asking the domain name server (DNS) for the IP address of the subscriber (MS_A, MS_B) on the basis of the name identifier reserved for the subscriber (MS_A, MS_B), the domain name server (DNS) sending the IP address corresponding with the name identifier to the new node, the new node (DXT_1 , DXT_2, DXT_3) sending the information on the new location of the subscriber (MS_A, MS_B) and a call return request to the old serving node (DXT_1 , DXT_2, DXT_3) by means of said IP address, the old serving node (DXT_1 , DXT_2, DXT_3) removing the information on the subscriber from its register and sending information on the call to the new node (DXT_1 , DXT_2, DXT_3), said call information comprising the name identifier of the other party to the call, the new node (DXT_1 , DXT_2, DXT_3) asking for a new IP address for said name identifier of the subscriber (MS_A, MS_B), the address server (DHCP) allocating the new IP address to the subscriber (MS_A, MS_B) and updating it on the domain name server (DNS) if the IP subnetwork has changed, or the address server (DHCP) retaining the old address of the subscriber (MS_A, MS_B) if the IP subnetwork has not changed, the address server (DHCP) giving the IP address to the new serving node, the new serving node (DXT_1 , DXT_2, DXT_3) asking the domain name server (DNS) for the IP address of the other party to the call on the basis of the name identifier of said other party, the domain name server (DNS) sending the IP address corresponding with the name identifier of the other party to the call to the new node (DXT_1 , DXT_2, DXT_3), the new node (DXT_1, DXT_2, DXT_3) asking the serving node (DXT_1 , DXT_2, DXT_3) of the other party to the call for call return by means of the IP address of said other party to the call, re-routing the call via the new node (DXT_1 , DXT_2, DXT_3).

7. A method as claimed in any one of the preceding claims, characterized in that updating the subscriber information in the home location register (HLR) comprises the steps of changing the subscriber information on the subscriber (MS_A, MS_B) in the home location register (HLR), the home location register (HLR) asking the domain name server (DNS) for the IP address corresponding with the name identifier of the sub- scriber (MS_A, MS_B), the home location register (HLR) sending the modified subscriber information to the node (DXT_1, DXT_2, DXT_3) serving the subscriber (MS_A, MS_B) on the basis of said IP address.

8. A method as claimed in any one of the preceding claims, characterized in that updating information on a group traffic group comprises the steps of changing the information on a group traffic group in the home location register (HLR) the home location register (HLR) asking the domain name server (DNS) for the IP address corresponding with the name identifier of the subscriber (MS_A, MS_B) belonging to the group, the home location register (HLR) sending the modified subscriber information to the node (DXT_1, DXT_2, DXT_3) serving the subscriber (MS_A, MS_B) on the basis of said IP address.

9. A method as claimed in any one of claims 1 to 8, characterized in that the name identifier is an MSISDN number, an ITSI number, an ISSI number and/or a name of a network element or a name of a terminal.

10. A telecommunication network comprising subscribers (MS_A, MS_B), serving network nodes (DXT_1, DXT_2, DXT_3) and at least one home location register (HLR) wherein subscriber information on the subscribers (MS_A, MS_B) is stored permanently, characterized in that the telecommunication network further comprises a domain name server (DNS) for controlling the location information on the subscribers (MS_A, MS_B) wherein at least one name identifier is stored for each subscriber (MS_A, MS_B) and wherein an IP address allocated to the subscriber (MS_A, MS_B) at the par- ticular moment is stored such that the serving nodes (DXT_1, DXT_2, DXT_3) are able to ask for the IP address of the subscriber (MS_A, MS_B) by means of said at least one name identifier, an address server (DHCP) arranged to allocate an IP address to the subscriber (MS_A, MS_B) when the subscriber (MS_A, MS_B) for the first time registers in any one of the serving nodes (DXT_1, DXT_2, DXT_3) in a new IP subnetwork and to update the IP address on the domain name server (DNS), an IP network through which messages are transferred between the domain name server (DNS), the address server (DHCP) and said serving nodes (DXT_1, DXT_2, DXT_3).

11. A network as claimed in claim 10, characterized in that the name identifier is an MSISDN number, an ITSI number, an ISSI number and/or a name of a network element or a name of a terminal.

12. A network as claimed in claim 10 or 11, characterized in that said at least one name identifier is stored in the domain name server (DNS) for each created subscriber (MS_A, MS_B).

13. A network as claimed in claim 10 or 11, characterized in that said at least one name identifier is stored in the domain name server (DNS) only when the subscriber (MS_A, MS_B) is registered in the network.