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Two Users Call Goes Silent Mid Call

                   Call Manager 6.1, first phone is a 7961 latest firmware the other is a 7941 latest firmware. These 2 phones have worked without issue for the last 4 years or so, around 6 weeks ago both users started intermittently experiencing an issue where the call will go silent, if they hit the volume button the audio comes back. I tried replacing the phones but the issue remains... any ideas?

I should mention we have many other 7941's and 61's at this site and no other users are experiencing issues.



Gaurav Purohit

replace hardware.

i am pretty sure if you try different firmware, it'll be no good.

William Bell


So, if I follow, you have two phones experiencing intermittent issues where they lose audio. You are running the same firmware as you have on phones that do not experience the issue. You have also swapped phones using "known good" hardware.

I initially thought this would point to a firmware issue. I had an issue a while ago where fragmented SCCP packets were causing intermittent problems. But since you are running the same firmware, this seems less likely.

You could check the network. Check the station interface counters, uplink counters, etc. Though, pressing the "volume" button fixes your issue. So, that actually points away from the network.

This leaves me with the following questions:

1. Is the audio issue a failure of both channels or just one? IOW, when they experience the issue is it a half-duplex audio stream?

2. Does the issue occur when these users call other IP phones? PSTN stations?

3. Does it occur when they are communicating to a specific call party? If yes, then do others experience the issue when communicating to the same party.

4. Does this occur for multiparty (conference) calls? If so, do they use hardware conferencing resources? Do they use the same conferencing resources?  If all of those questions are yes, check your DSPs.

-Bill (

HTH -Bill (b) (t) @ucguerrilla

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