Hope all is well. I added an extension to my PBX, for some reason it works for one minute after I sync the settings and then it just rings as busy anytime you call into the extension.
The sip show peers shows the extension is active. The grandstream settings panel shows the phone is registered with the PBX. The call history on the phone shows incoming calls, but none go through.
DND is off on the phone. I’ve factory reset it twice. Whenever you call from the internal network it just shows “busy” and you hear the beeps. Same thing from the outside. Not sure what it can be.