Could you be more specific about the path of the call? Sometimes this can be caused by physical problems with analog lines, like FXO/FXS (or E&M) lines that are getting interference. Switching a cable might help. Otherwise, some more details about the physical setup would be helpful (including wiring distances and such).
I had a similar problem with our system right after we upgraded to 12.2 on our 4224. The Cisco TAC engineer said:
Can you configure on dial-peer voice 100 or 200 "incoming called-number ." on any of them. I want to make sure that the incoming call match the no vad statement on them. If the incoming called doesn't have a match, it will default to dial peer 0 with is vad enable. Please take a look at this URL sor more information:
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The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
Topology: IP Phone > Switches > Microsoft NPS setup to forward 802.1x
proxy to > ISE 2.1 patch 3 Authentication: EAP-TLS using Cisco MIC SANs
Phone Models 802.1X support? 802.1x flavor Addtl Comment EAP-MD5 EAP-TLS
Cisco 3905 Y Y N Cisco 6911 Y Y N Cisco ...