Hi,
what you mean with "reach out to external NTP servers"?
The phones only contact those NTP servers, that they get assigned via the CUCM settings.
So, if the use the wrong NTP's, check the Date/Time Group that is assigned to the device pool.
And then check the corresponding NTP references, that were assigned to the relevant Date/Time Group.
The phones don't get the NTP's out of nowhere just like that.
If they use wrong NTP's, then someone configured the wrong one's.
