The present document 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.

NOTE: The term GSM MS is used for any type of MS supporting one, or combinations, of the frequency bands specified in 3GPP TS 45.005.

The present document outlines how the requirements of the 3GPP TS 22 series Technical Specifications (especially 3GPP TS 22.011) on idle mode operation shall be implemented. Further details are given in 3GPP TS 44.018 and 3GPP TS 45.008.

Clause 2 of the present document gives a general description of the idle mode process. Clause 3 outlines the main requirements and technical solutions of those requirements. Clause 4 describes the processes used in idle mode. There is inevitably some overlap between these clauses. Clause 5 describes the cell change procedures for a MS in group receive mode. Clause 5a describes the cell change procedures for a MS in broadcast/multicast receive mode.