The BSC serving the Qinghai-Tibet office responds to the handover failure, and the cause value is that the requested speech version is unavailable.
The supported speech version capabilities reported by terminals are as follows:
Sagem 2 W handheld terminals support both full-rate and half-rate speech versions, and the half-rate speech version has a higher priority.
SED 2 W handheld terminals also support both full-rate and half-rate speech versions, and the full-rate speech version has a higher priority.
Messages reported by a Sagem 2 W handheld terminal
Messages reported by a SED 2 W handheld terminal
The following table describes the speech version capabilities supported on the network side.
When a terminal initiates an inter-MSC handover, it sends a Handover Required message to the local MSC to request a handover request. The local MSC selects a speech version from all the stored terminal speech versions based on their priorities and then sends it to the peer MSC. For the Sagem 2 W handheld terminal, the half-rate speech version has a higher priority. When this terminal is handed over from the Lanzhou office to the Qinghai-Tibet office, it requests for half-rate speech version 1. However, the network for the Qinghai-Tibet office supports only full-rate speech version 1, and it accordingly rejects the terminal request. As a result, the handover fail.