Digital Voice Interfaces
Digital voice interfaces are provided to Cisco routers by use of digital voice
trunking cards and Digital Voice Processor (DVP) voice compression modules
(VCMs). Digital voice trunking cards interface most commonly with ISDN BRI
and PRI lines. By utilizing the individual channels on each line, it allows for a
single line to support two voice lines using BRI and up to 23 lines using PRI in
the U.S., and up to 30 in Europe. Digital voice processor VCMs allow a router to
take a voice conversation and compress it down to as small as 5.3 Kbps,
depending on the method utilized, as opposed to a 56 Kbps channel.This allows
for a much greater utilization of available bandwidth.