The voice conference bridge (VCB) application provides a simultaneous communication path between two or more voice circuits. VCBs are deployed in a central location with remote devices connected to the bridge via the 7705 SAR over an IP/MPLS or TDM network. Inputs to the VCB are 4-wire E&M analog interfaces.
VCBs can be used as a conference bridge with any-to-any connectivity (all branches participate) or as a bridge in broadcast mode where one branch broadcasts to the other branches that are in listen-only mode.
The main VCB applications are:
Land Mobile Radio (LMR) interconnection
Both voice conference mode and broadcast mode can be used for this application.
analog multi-terminal teleprotection interconnect for electrical utilities
For multi-terminal teleprotection applications, VCBs allow all teleprotection relays to communicate with each other in order to make the appropriate switching decision in the event of a fault.
The VCB application uses Mu-Law and A-Law encoding, similar to PCM. Table: VCB Modularity shows the modularity for a VCB on the Integrated Services card.
Encoding Scheme |
Number of Bridges per Integrated Services Card |
Number of Branches per Bridge |
Total Number of Branches per Integrated Services Card |
|---|---|---|---|
Mu-Law (North America) |
16 |
24 |
384 |
A-Law (rest of world) |
16 |
32 |
512 |
A VCB SCADA bridge is created using the config>scada bridge-id command and a branch is created using the config>scada>branch branch-id command.
Larger bridges can be built by cascading individual bridges internally within a single Integrated Services card. Larger bridges can be cascaded across multiple Integrated Services cards by using an E&M link or a channel group encapsulated for cem (TDM).