scope:

This European Telecommunication Standard (ETS) specifies the procedures used at the radio interface (Reference point Um as defined in GSM 04.02) for normal operation and invocation of MultiParty supplementary services. In GSM 04.10 the general aspects of the specification of supplementary services at the layer 3 radio interface are given. GSM 04.80 specifies the formats and coding for the supplementary services. Definitions and description of supplementary services are given in GSM 02.04 and the GSM 02.8x and 02.9x-series.