Phone loses IP and need reboot to aquire one


Good day,

We had an issue the other day, most of our Phones (GXP16XX) lost connection to UCM.

There is no IP in the phone and extension status in UCM is Unavailable, we had to reboot the phones

Either from UCM or manually to acquire new IP and work.

How to troubleshoot this? I already check if access switches connected to did shutdown but they did not.



If the phone has no IP, how were you able to initiate a reboot command from the UCM to a phone (with no IP)?


→Value-added Features→Zero Config→Zero Config Settings Then Reboot

Didn’t check if I was able to ping those IPs but on the phone display itself there is no IP showing

And can’t make or receive calls.


16xx firmware ? I remember something like this on old fw i think.



it look like phone do not show IP but it have.
You DHCP pool is not full ?
As this can happens when DHCP do not provide refresh.


Unlikely, the pool is /22 mask is 1024 IPs and total phones won’t exceed 100.


As sip notify with IP work then phone must have IP (old) but my guess it is not refreshed (No ip).
I think you need mirror port and see what is going there when there is no IP.