Some PJSIP Extensions will not register that did before

Hi all

I have been using the latest distro and all updates applied with about 30 extensions on it for several months. During the last week I have several extensions that have stopped registering. Inbound calls go straight to voicemail but out bound work fine.

I’m using PJSIP and the sip driver is disabled.
I have deleted the extensions and users, recreated them.
Setup the extensions on several known working phones without success.
Setup other extensions on the handsets that have the problem and they work so its defiantly a server side issue.

Any idea how to trouble shoot this as the logging shows the extensions register but they do not create a contact?

Thanks in advance.

Hi everyone, can anyone help me troubleshoot this?