The procedure for successful GSM to UMTS handover from MSC-B back to 3G_MSC-A without circuit connection is shown in Figure 28
. The only difference with the Figure 26
, is that no circuit release is needed between 3G_MSC-A and MSC-B.
The procedure for successful GSM to UMTS handover from MSC-B to 3G_MSC-B' is shown in Figure 29
The procedure consists of two parts:
a subsequent handover from MSC-B back to MSC-A as described in subclause 7.4.1 (the same procedures apply if MSC-A is replaced by 3G_MSC-A); and
a basic GSM to UMTS handover from MSC-A to 3G_MSC-B' as described in subclause 8.2.2.
The only difference to the equivalent Figure 27
is the omission of the circuit and handover number allocation signallings.