Abstract: A method for recovering group data between mobile systems, which incorporate at least one first mobile system, at least one second mobile system, and mobile stations, the method comprising the steps of maintaining group data in a first database of the first mobile system, maintaining group data in a database of the second mobile system. In the method, a recovery request is made for recovering the group data, the second mobile system generates one or more virtual attachment requests for the first database of said group, the second mobile system transmits the virtual attachment request to the first database of the first mobile system, in response to the first virtual attachment request, the group data are updated in the first database.

Abstract: The present invention relates to preventing inconsistency between the data maintained in a master exchange and a backup exchange in a telecommunication system. To ensure a reliable data distribution, the system maintains a copy of the master exchange data in a slave exchange. When the slave exchange receives data from the master exchange or the backup exchange, the received data or the corresponding data previously stored in the slave exchange is selected for use on the basis of comparison of the information included in their update information. That is, the data stored in the slave exchange is sent to the exchange having sent the received data if the data stored in the slave exchange is selected for use; the received data is sent to the master exchange if the data received from the backup exchange is selected for use; and the received data is stored in the slave exchange if the received data is selected for use.

Abstract: A method for obtaining subscriber data in a mobile communication system includes a home data base and a visitor data base. The home data base stores data about subscribers to the home data base and an age label noting the previous updating of the data of each subscriber. The home data base data is updated in response to update requests of subscriber data. The visitor data base stores data about subscribers registered in the visitor data base and in each label indicating the previous updating of the data of each subscriber. The visitor data base data is updated in response to updating requests of subscriber data. There is a method for recovering the data of visiting subscribers between mobile communication systems and/or between nodes of the mobile communication network.

Abstract: A fault tolerant change distribution method in a distributed database system including at least two separate intercommunicating databases. At least part of the stored data is identical in the different databases. The changeable data items of the databases are provided with state fields, whereby, after a data item has been added, deleted or modified, the state field of the respective data item is set in a state which indicates that the change should be transmitted to another database. When the change has been transmitted to the other database, an acknowledgement of receipt of the change is awaited from the other database, whereafter the state field of the data item is set in a state which indicates that the change has been transmitted.