| 摘要 |
The GSM system includes a protocol for reestablishing a lost call. A problem occurs if the call is lost after an inter-MSC (MSC-A, MSC-B) handover, resulting in that the system does not know into which MSC the subscriber data of a mobile station (MS) has been updated. If the MSC has changed during the call, and the MS is no longer able to contact the cell served by the original MSC-A, the call will be lost. In the method according to the invention, the MSC serving the location area of the mobile station detects a start message (1') transmitted by the mobile station and containing the Last Location Area Identifier of the mobile station. Based on the Last Location Area Identifier, the second center MSC-B, which detects the start message (1'), determines the first center MSC-A in whose area the call was started. Following this, the second center MSC-B may establish a connection to the first center MSC-A. At this stage, the centers (MSC-A) and MSC-B) reverse roles and the method proceeds as in a conventional inter-MSC handover. The method of the invention for establishing a connection may also be applied to a satellite system that uses the GSM system network structure.
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