Question: In areas where both MSC-based services and SGSN-based services are provided, how is discrimination done between the allocation of TMSIs for these two service types within the TMSI structure?
Option 1: Using the least significant bit, with values 0 for MSC-based and 1 for SGSN-based services.
Option 2: Using the 2 most significant bits, with specific value allocations for each type of service (e.g., 00, 01, 10 for VLR/MSC and 11 for SGSN).
Option 3: By incorporating a unique identifier for each service type within the middle bits of the TMSI.
Option 4: Discrimination is not required at the TMSI level for co-existing MSC and SGSN services.
Explanation: To ensure proper differentiation between TMSIs allocated for MSC-based services and those for SGSN-based services in shared areas, the two most significant bits of the TMSI are used for this purpose. This approach allows for clear discrimination, with defined bit values assigned to each service type (VLR/MSC: 00, 01, 10; SGSN: 11), facilitating efficient and error-free service provisioning in mixed-service environments.