If it had been a keepalive timeout then the phone would have reset after the call was over. Resetting of the phone during an active call would actually point to an issue on the phone / switch(port) or someting else on the network. You can also capture the console logs from the IP phone depending upon the frequency of the issue> if its possible to setup a packet capture on one of the swicthports where the affected phone is connected it would provide the exact details. Reason code of 6 in the trace above is a generic 'Network connectivity' issue message. It would also be recommended to look for any errors on the switchport where these phones are connected.
6 ConnectivityError - Network communication between the device and Unified CM has been interrupted. Possible causes include device power outage, network power outage, network configuration error, network delay, packet drops, and packet corruption. It is also possible to get this error if the Unified CM node is experiencing high CPU usage. Verify that the device is powered up and operating, verify that network connectivity exists between the device and Unified CM, and verify that the CPU utilization is in the safe range (you can monitor this via the CPU Pegging Alert in RTMT).
You should check the Event Viewer - Application and System logs from the Call manager to get more details on this and see if any other phones were affected with this.
As Manish has said, this may be a network issue that has caused this because it doesn't look like there was a reset initiated on the phone or the call manager.
More details of error messages on call manager can be found here:
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 ...
This document describe how DST changes and how time changes are
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setting the clocks forward 1 hour from standard time during the summer
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