This TS gives an overview of the tasks undertaken by a GSM Mobile Station (MS) when in idle mode, that is, switched on but not having a dedicated channel allocated (e.g. not making or receiving a call), when in group receive mode, that is, receiving a voice group call or voice broadcast call but not having a dedicated connection or when in broadcast/multicast receive mode, that is, receiving an MBMS session but not having a dedicated channel allocated. It also describes the corresponding network functions. The idle mode functions are also performed by a GPRS MS as long as no dedicated channel is allocated to the MS. The idle mode functions are also performed by a CTS MS as long as the CTS MS is in manual mode GSM only or in automatic mode under PLMN coverage.