Sep 16

One way calling over Cisco Voice Gateway using MGCP PRI

Had an issue where a site was not able to dial local numbers over their local PRI on their MGCP (Cisco) Gateway. Inbound calls worked from the PRI. I found that the PVDM had a bad DSP on it. The DSP was the DSP that converted the local IP packets into the protocol for the PRI.

After replacing the PVDM, the local calls started working.

Here is how to tell if a DSP has failed.
Issue the following command on the router, you will notice DSP 1 & 2 are good and 3 is bad.

show voice dsp group all

MR.BEERĀ®

GoatRouter#show voice dsp group all
DSP groups on slot 0:
dsp 1:
State: UP, firmware: 24.3.7
Max signal/voice channel: 16/16
Max credits: 240
num_of_sig_chnls_allocated: 16
Transcoding channels allocated: 1
Group: FLEX_GROUP_VOICE, complexity: FLEX
Shared credits: 210, reserved credits: 0
Signaling channels allocated: 14
Voice channels allocated: 0
Credits used: 0
Group: FLEX_GROUP_XCODE, complexity: MEDIUM
Shared credits: 0, reserved credits: 30
Transcoding channels allocated: 0
Credits used: 0

dsp 2:
State: UP, firmware: 24.3.7
Max signal/voice channel: 16/16
Max credits: 240
num_of_sig_chnls_allocated: 16
Transcoding channels allocated: 3
Group: FLEX_GROUP_VOICE, complexity: FLEX
Shared credits: 150, reserved credits: 0
Signaling channels allocated: 10
Voice channels allocated: 0
Credits used: 0
Group: FLEX_GROUP_XCODE, complexity: MEDIUM
Shared credits: 0, reserved credits: 90
Transcoding channels allocated: 0
Credits used: 0

dsp 3:
State: FAIL, firmware: 0.0.0 —————-> This DSP has failed
Max signal/voice channel: 16/16
Max credits: 240
num_of_sig_chnls_allocated: 1
Transcoding channels allocated: 0
Group: FLEX_GROUP_VOICE, complexity: FLEX
Shared credits: 240, reserved credits: 0
Signaling channels allocated: 1
Voice channels allocated: 0
Credits used: 0

If you had one way calling on your PRI, was this your problem or something else?