Interface Configuration Guide 7705 SAR Interfaces
Edition: 01 3HE 11011 AAAC TQZZA 177
In order to put the bridge into the normal state, it must be reset. This can be manually
initiated by the operator with the squelch reset command, or it can occur
automatically after a configured time if the squelch-recovery command is set to
auto.
For MDDB, because different algorithms are needed to detect squelch conditions at
low-speed and high-speed rates, interface speed selection is required. The interface
speed is set at the bridge level.
3.6.5 Voice Conference Bridge
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 23
shows the modularity for a VCB on the Integrated Services card.
Table 23 VCB Modularity
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
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