Voice Compression Module
267
Voice Compression
Module
The optional Voice Compression module (VCM) provides one T1 or E1 port. It is
similar in function to the CBR module, but it employs compression algorithms that
allow more voice calls to be placed through the same bandwidth.
The incoming voice signal is carried on one or more of the T1/E1 port’s 24/30
channels. The voice data in each DS0 channel is in PCM format. This data is
compressed by the DSP, and the output from the DSP is encapsulated into FRF.11
packets by the host CPU on the VCM daughtercard. The packets are then passed
to the mother board through the PCI interface, handed over to the AAL5 SAR, and
transmitted to the ATM interface.
In the reverse direction, compressed voice packets are received by the SAR on the
ATM interface in FRF.11 format. The packets are then passed to the VCM
daughtercard via the PCI interface. The packets are unpacked by the daughtercard
CPU before they are handed to the DSP, which decompressed the voice data and
plays out the voice onto the T1/E1 PCM interface.
Table 40
Multi-point Video Conferencing Routing Table (Remote Unit #1111)
Destination #
Tx vpi/vci
Rx vpi/vci
Speed
Status
2222
0/1
0/2
384k
idle
3333
0/1
0/3
384k
idle
4444
0/1
0/2
384k
active
Table 41
Multi-point Video Conferencing Routing Table (Remote Unit #2222)
Destination #
Tx vpi/vci
Rx vpi/vci
Speed
Status
1111
0/2
0/1
384k
idle
3333
0/2
0/3
384k
idle
4444
0/6
0/7
384k
active
Table 42
Multi-point Video Conferencing Routing Table (Remote Unit #3333)
Destination #
Tx vpi/vci
Rx vpi/vci
Speed
Status
1111
0/3
0/1
384k
idle
2222
0/3
0/2
384k
idle
4444
0/12
0/13
384k
active
Table 43
Multi-point Video Conferencing Routing Table (Central Unit #4444)
Source
Tx vpi/vci
Rx vpi/vci
DS0s
1111
0/2
0/1
channels 0-5
2222
0/7
0/6
channels 6-11
3333
0/13
0/12
channels 12-17
