GSM Inter MSC Handover Call Flow

Handing over a GSM call is a complicated procedure. It is even more so when the source and target GSM cells are controlled by different MSCs. The following call flows analyze the different steps involved in a inter-MSC handover:

  • The source BSC analyzes the signal quality measurement reports and initiates a handover.
  • The source MSC finds that the call needs to be handed over to a cell controlled by a different MSC.
  • The source MSC and target MSC interact and then command the UT to move to the new cell.
  • The target MSC informs the source MSC when the call has been successfully handed over.
  • The source MSC releases the radio resources for the call. Note that the call is still routed via the source MSC.

The handover sequence diagrams present the full message flow from different angles: