finally terminating the call. The traffic channels handle the actual payload. The following logical channels are defined in GSM: TCHf Full rate traffic channel. TCH h Half rate traffic channel. BCCH Broadcast Network information, e.g. for describing the current control channel structure. The BCCH is a point-to-multipoint channel (BSS-to-MS). SCH Synchronisation of the MSs. FCHMS frequency correction. AGCH Acknowledge channel requests from MS and allocate a SDCCH. PCHMS terminating call announcement. RACHMS access requests, response to call announcement, location update, etc. FACCHt For time critical signalling over the TCH (e.g. for handover signalling). Traffic burst is stolen for a full signalling burst. SACCHt TCH in-band signalling, e.g. for link monitoring. SDCCH For signalling exchanges, e.g. during call setup, registration / location updates. FACCHs FACCH for the SDCCH. The SDCCH burst is stolen for a full signalling burst. Function not clear in the present version of GSM (could be used for e.g. handover of an eight-rate channel, i.e. using a "SDCCH-like" channel for other purposes than signalling). SACCHs SDCCH in-band signalling, e.g. for link monitoring