I have a site that uses a cable modem with a dynamic ip . . Generally ,the ip address stays the same for months unless the modem gets rebooted . For remote ip phones I have configured the UCM wiith a dyndns account so even if it changes ,it should still work . Question is ,can i configure the local phones with the dyndns address also ,or is that only designed to be used remotely over the internet . I know that if we try to access our server locally ,we can not use the dyndns address , we can use it only remotely through the internet . I am just concerned that in the unlikely event the ip address changes in middle of the day , then all their local phones will stop working .


I tell you my experience, one of the first rules I was taught when I started to know VoIP, is that the main prerogative is to have a static IP, for a variety of reasons I have consequently done my tests, with dynamic IP there were always problems, it was a continuous chasing a solution.


It sounds like you are pointing the local phones to the public IP address of the UCM. Is there a reason that you don’t point the local phones to the LAN IP address of the UCM?


You are correct. I was working with a remote phone and got confused.