VCB can be configured in one of four applications. These applications are set at the card level. Each application uses a bridging algorithm that determines which branches control the management of the bridge and transmission of signals:
VCB
One branch talks and all other branches on the bridge can hear.
broadcast
Only one branch on the bridge (fixed as branch 1) has control of the bridge to transmit, and all other branches are in listen-only mode.
VCB branch initiate
Branches on the bridge are only enabled (unmuted) when the attached base station signals its presence by grounding the M-lead on the interface connected to the bridge. Upon receiving the grounded M-lead via T1/E1 ABCD bits or TDM PW signaling, the bridge unmutes the associated branch. When the ground is removed, the branch is muted again.
teleprotection
Each teleprotection relay transmits state information on discrete frequencies so that each relay can both hear what the other relays are transmitting as well as transmit its own information to the other relays.