We had a major network outage impacting our whole business. It was noted that we had 10% of our phones didnt register back to cucm.
They displayed as being un registered in cucm with a valid ip address which we could ping and connect too.
TFTP option 150 is set in DHCP scope.
Phones worked before outage
We tested unplugging and phone and plugging back in - it still stuck on unregistered.
After some hours, they look like they are coming back to life. In the past we have had similar issues too with registration of phones on a smaller scale.
Can anyone help explain or has an idea whats going on here? My thoughts point towards DHCP issues but not sure how to troublehsoot this moving forward?