As the title says, I have a fairly new installation of a Grandstream UCM6208 with GXP2160 phones. I have one user that has had an issue pop up today (phones have been in use for about two weeks now) where when the user attempts to answer some calls they drop after a second of silence, then “Service Unavailable” is shown on their phone.
I have no idea what could be causing this, outbound calls and inbound calls answered by other users are not having issues. When I look at the extensions on the UCM web portal that extension shows as available and I am able to ping it and log on as admin on the extension’s web portal.
Has anyone else had a similar issue?