7 Compatibility Issues

23.0533GPPRelease 17Service descriptionStage 2Tandem Free Operation (TFO)TS

Since the radio interface is not modified, there is no compatibility issue with the MS. It is up to the second TRAU to make sure that what it sends to the BTS is compatible with the existing.

The compatibility issue is with end systems not supporting TFO.

The TFO negotiation message synchronisation patterns should be chosen such that no other system uses such a pattern for another purpose, and that this pattern cannot be generated by a peer entity which is not supporting TFO. This does not preclude other systems than GSM or UMTS to use TFO since the type of system is part of the negotiation mechanism.