The CBC, as a part of the core network (CN), is connected to multiple RNCs through the Iu-BC interface. The CBC manages the CBS messages, whereas the UMTS radio access network (UTRAN) performs transparent transmission of the CBS messages from the CBC.

A common traffic channel (CTCH) needs to be configured for each cell supporting the CBSfeature. The CTCH is mapped onto a FACH.

In the release of RAN14.0, the second CBC can be configured as a redundancy CBC for the disaster preventing.