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AMA-CUCM Troubleshooting: Best Practices for Reading Trace Files

Changing the NTP source in CUCM from CLI and other helpful information:


Sometimes, you may want to change the NTP source of your Cisco Unified Communications Manager. Here’s some information that might help with the procedure.

To view your current NTP configuration:

To test NTP reachability, clock drift & stratum:

Notice that the NTP status command shows as my only NTP reference. If you wanted to add a new NTP reference you could use the command “utils ntp server add X.X.X.X”. Before adding the new NTP reference, you might want to make sure you can reach the device first:

Once you confirmed connectivity, you can proceed: “utils ntp server add X.X.X.X”

Furthermore, if you want to delete the old NTP reference for whatever reason: “utils ntp server delete”

Once you’re ready to go; you can manually restart the NTP service:

Notice the old reference is now gone, and we only have 1 NTP server with an IP address of

After doing these changes, you might have to log into the CUCM admin page and specify a new NTP reference for your Date/Time Groups:

Go to CUCM administration page >> System >> Phone NTP reference >> Add New:

Once you have that covered go to System >>Date/Time Group >> Choose your DTG >> Add Phone NTP reference:

At this point you can add the new NTP server and remove any NTP servers you will no longer need.


Changing the NTP server in the Date/Time Group will reset all the devices in the Device Pools associated to the Date/time group in question. If you are using a CUCM version 8.6+ and the environment is virtualized, you will get a message on your Admin home page letting you know you’re running on a trail period. This is expected. Please contact TAC at or call 1800-553-2447 to have a license re-host for your virtual MAC.

Useful Documents/information:

Administration guide for CUCM 8.6 / NTP settings:

Issue with Time Synchronization on Cisco Unified Communications Manager with Network Time Protocol Server – last updated 2010

CUCM NTP Command line reference for CUCM 8.6:

CUCM NTP Command line reference for CUCM 10.X:


Settings that could affect your Virtual License MAC CUCM 8.X:


Cisco Employee

Gem of  a doc ! High 5 :) 


Great post!  Thanks.


I heard someone say that changing the NTP source doesn't cause re-licensing in later versions.  If that's true, what version did that start?


Maybe 8.6 is the last version that needs to re-license from an NTP change. 


FYI i just changed the NTP from an old to a new server we just commissioned, and we did not have to mess with licensing. We are on version 10.5.2 (

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