Poor audio quality on CUCM 8.5 and 7942G IP Phones

[fuhrersk8]

                   Hello guys!

     On a deployment with a main site and two remote sites, users on main site are experiencing poor audio quality. It is not choppy or intermittent audio, it is like a loudspeaker kind of audio quality, like if users are talking in a tunnel. But between the sites, including main site, audio quality is good, the usual dry and clear natural VoIP quality. 

The phones are all 7942G. The phones are connected to Catalysts 3750X with auto qos on access ports. Between the sites is g729 and on each site is g711.

I configured CAC between the sites. Bandwidth is not a problem because between the sites there are 3Mbps and on main site all phones communicate through the Catalystss 3750X and core switch Catalyst 4506E. Also, this implemrntation is not in full produciton yet, so all phones are not being used still (total phones are 125 phones).

I just Resync Bandwith on main site and audio quality goeas back to the usual dry and clear natural VoIP quality. But what should be causing this kind of audio quality degradation on main site?

What recommendations do you have guys? Thanks in advanced!

[Rob Huffman · Accepted solution]

Hi Nephtali,

There is a setting that is applied to newer phones like the 7962 and not

older phones like the 7940. I would try disabling this setting as a first step;

"Advertise G.722 Codec"

This can be done on the individual IP Phone(s) for testing and then

in Enterprise Parameters if successful.

Cheers!

Rob

"Show a little faith, there's magic in the night" - Springsteen

[fuhrersk8]

Excellent Rob. Since this implementation is not in full effect yet, I will disable the parameter globally since users prefer the normal audio quality and not the enhanced one. Thanks a lot!

[fuhrersk8]

Exactly my friend.

[Rob Huffman]

Hi Nephtali,

You are always welcome my friend

It's funny ...I have some user who love, love, love the sound of calls

with g.722 and some who hate it. It's one of those;

"you can't please all the people, all the time" type things

Nice work!

Cheers!

Rob

"Show a little faith, there's magic in the night" - Springsteen

[michalkaska99 · Accepted solution]

Hallo,

I have similar issue with 7942/62 phones on CUCM 8.0. The speech quality while using codec g.711 sounds like from tunel. I am using g.722 codec for internal calls and in this case call quality is great, but customer has SIP turnk to PSTN and here is supported only g.711.

Speech quality on old 7940 phones with g.711 codec is much better that with this wideband phones.

Is some way how change the speech quality on these phones?

It is really terrible explaining customer, why 7912 phones have better voice quality.

Michal

[fuhrersk8]

Try disabling the following parameters on the phones:

• Advertise G.722 Codec 
  
• Wideband Headset UI Control
  
• Wideband Headset
  

Also, try Resync bandwidth on the Region with the Voice Gateway.