A broadcast control channel (BCCH) is a point to multipoint, unidirectional (downlink) channel used in the Um interface of the GSM cellular standard.
The BCCH carries a repeating pattern of system information messages that describe the identity, configuration and available features of the base transceiver station (BTS).
These messages also provide a list of absolute radio-frequency channel numbers (ARFCNs) used by neighboring BTSs.
This message pattern is synchronized to the BTS frame clock.
[2] Any GSM ARFCN that includes a BCCH is designated as a beacon channel and is required to transmit continuously at full power.