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New Member

CUCM Node FQDN in phone config file


I am running in to an issue: the CUCM node names a phone receives are not the FQDN, but only the host name. This ofcourse is the case because they are configured like that in System -> Servers. Most phones do get from DHCP the correct domain name, so they look up the hostnames without a problem.

However, now I have a phone in another site, which from DHCP gets a different domain name. This phone is now looking for hosts in a subdomain where it cannot find them, and thus cannot register with those CUCM nodes.

I also figured out that if a phone can't resolve those hosts, it tries to register with the node at the TFTP server IP instead. However, when that node is not in the CUCM Group for that phone, it will get rejected.

Is there a way to make CUCM push out FQDN node names in the phone config files?

Kind regards,


Everyone's tags (1)

Any reason you couldn't

Any reason you couldn't change it to IP addresses rather than host names?

Hope that helps!


New Member

No technical reason, no. But

No technical reason, no. But it is easier to have hostnames, so you can see more easily which server is which, and more specifically, where it is located.

Just change the names in

Just change the names in System -> Servers to FQDN ;-)


But....I'd strongly suggest you do one server at a time, and give time between each server name change. If you don't, the phones won't recognise the security certificates from CUCM, will fail to register, and you'll have to delete the TLS file from every phone. (Either manually or use a third party tool)


Also, be *VERY* careful as you type in the new FQDN. If you mis-type it and hit "Save", you risk breaking your cluster. (Been there, done that, got the scars to prove it) If you're running on VMWare, a cluster-wide snapshot could be your friend here (regardless of whether Cisco support them or not)


Oh, and before you start, make sure your DHCP servers are dishing out DNS Server IP addresses BEFORE you make any changes.



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Cant you modify the the

Cant you modify the the domain name that the DHCP scope has and make sure it matches with the domain associated with CUCM? Also make sure that the DNS server entries are correct and this should work provided Cisco is nowadays pushing everyone to use hostnames.

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