Extension Port

I have an issue with FreePBX

If i change the port on one extension the phone will not register with that new port . For some reason is still registers using the old port default port 5060 .

I would like to keep internal phones on 5060 and move only one extension t 55060 . It works with older versions of asterisk only and it also works in Trixbox CE.
For some reason i was unable to make it work with FreePBX

Any help would be apriciated

Did you change the port the phone uses? Just changing it on the extension page in FreePBX does not change it on the phone configuration.