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, or when in group receive mode, that is, receiving a group call or broadcast call but not having a dedicated connection. 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 GSM 05.05.

The present document outlines how the requirements of the GSM 02 series Technical Specifications (especially GSM 02.11) on idle mode operation shall be implemented. Further details are given in GSM 04.08 and GSM 05.08.

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.