MoH quality issues on external calls

[jogolev]

Hi,

We have CUCM 7.1 subscriber running MoH unicast stream as G.711

PRI gateway is MGCP controlled from CUCM.

MoH works just fine for internal calls.

But when placing on hold calls to/from PSTN voice quality is pretty poor on other side (cellphone or landline).

It is not choppy but has kind of "shhhhhhh" sound added to the music.

I've checked 'show call active voice' on GW and there are no lost/late packets and latency/jitter is 3ms to CUCM.

Any tips on troubleshooting or workarounds for this?

[Jonathan Schulenberg]

That sounds exactly like G.729 which can't compress music well (it was designed for human speech).

Assuming CUCM really is doing G.711 to the router and the audio isn't getting proxied through a transcoder/MTP (show call active voice compact should show this by showing g711ulaw and the IP address of the MoH server) the next question is what does the carrier side look like? I have seen a lot of carriers doing IADs or other VoIP to an on-site router and then turning it into a PRI for handoff to the CPE. These providers are usually running G.729 internally which will wreck your MoH audio. The only way to fix it would be to get them to stop using G.729.

Please remember to rate helpful responses and identify helpful or correct answers.

[Jon Clark1]

January 2016

My customer had a similar problem where internally MoH sounded fine but external callers would hear poor MoH and even cutting out.

We spent a good while playing with sound files but the ultimate solution came when we compared Cisco's Default MoH sound file (pulled it down via SFTP from CLI) settings to the file we have been using.

Using Audacity 8000hz Microsoft u-law wav did not improve the sound much.  When the customer used SoundForge and the following settings the quality finally improved greatly...

            16-bit PCM wav file

• Stereo
• Sample rates of 48 kHz

Hope this help.

JC