5 Interaction with supplementary services

22.0533GPPRelease 17Service descriptionStage 1Tandem Free Operation (TFO)TS

5.1 General

This clause defines the interactions between supplementary services and TFO.

Neither TFO nor attempted TFO establishment shall interfere with the provision or invocation of any supplementary services.

5.2 Explicit Call Transfer (ECT)

Following call transfer, the new call route is evaluated and TFO applied if possible, otherwise normal operation applies.

5.3 Call wait/Call hold

Following the establishment of another call, the new call route shall be evaluated and TFO applied if possible, otherwise normal operation applies.

5.4 Multiparty

Where more than two parties are involved in a call, TFO may not be applicable. As a result, when a two-party TFO call is extended to multi-party, all the links shall revert to normal operation.

5.5 Service Announcements

TFO shall not disrupt the provision of call progress or similar speech announcements to the user which originate in any of the networks routing a call.