This TS specifies the procedures used at the radio interface (Reference point Um as defined in TS 04.02
) for normal operation, registration, erasure, activation, deactivation, invocation and interrogation of call transfer supplementary services. Provision and withdrawal of supplementary services is an administrative matter between the mobile subscriber and the service provider and cause no signalling on the radio interface.
The following supplementary services belong to the call transfer supplementary services and are described in this TS:
Explicit Call Transfer (ECT)