Method and arrangement for handling network specific subscriber data during roaming by use of sim card information storage

A method for implementing the acquisition of data relating to network-specific supplementary services in a telecommunications system, which comprises at least two mobile systems, which in turn comprise user terminals (11) and mobile networks (10, 30) comprising mobile switching centres (32) and subscriber databases (24, 31, 34), at least one user terminal (11) functioning not only in a home network (10) but also in at least one visited network (20, 30), said terminal supporting at least one network-specific supplementary service in said visited network, the method comprising the steps of

• initiating by said at least one user terminal the registration in the visited network, which comprises at least one network-specific supplementary service;
• transferring the subscriber data relating to the common services of the home network and the visited network, in connection with the registration, from the subscriber database (14) of the home network for temporary storage to the subscriber database (34) of the visited network,
• characterized by, in addition,
• permanently storing the subscriber data relating to the network-specific supplementary services of the visited network in the identity module (12) of the user terminal (11),
• transmitting, at least in connection with the registration in the visited network, the subscriber data relating to the network-specific supplementary services from the identity module (12) of the user terminal (11) for temporary storage to the subscriber database (34) of the visited network.

A method for updating subscriber data relating to network-specific supplementary services in a telecommunications system, which comprises at least two mobile systems, which in turn comprise user terminals (11) and mobile networks (10, 30) comprising mobile switching centres (32) and subscriber databases (24, 31, 34), at least one user terminal (11) functioning not only in a home network (10) but also in at least one visited network (20, 30), said terminal supporting at least one network-specific supplementary service in said visited network, the method being characterized by

• permanently storing subscriber data relating to the network-specific supplementary services of the visited network in an identity module (12) of the user terminal (11),
• receiving a request of change concerning the subscriber data relating to a network-specific service,
• inquiring of a subscriber database (14) of a home network for a routing address to a subscriber database (34) of a subscriber's location area for routing the subscriber data relating to the network-specific supplementary services from a network (30) providing the service to the subscriber database (34),
• establishing a radio connection between the user terminal (11) and the network (30) providing the service,
• performing the data transmission associated with the network-specific supplementary services between the user terminal (11) and the network (30) providing the service, for changing the subscriber data in the identity module (12),
• releasing the radio connection.