Requirements ------------------------------------------------------------------------------21 series
Service aspects ("stage 1")------------------------------------------------------------ 22 series
Technical realization ("stage 2")------------------------------------------------------23 series
Signalling protocols ("stage 3") - user equipment to network-------------- 24 series
Radio aspects---------------------------------------------------------------------------- 25 series
CODECs 26 series
Data 27 series
Signalling protocols ("stage 3") -(RSS-CN) 28 series
Signalling protocols ("stage 3") - intra-fixed-network 29 series
Programme management 30 series
OAM&P and Charging 32 series