All Calls Routed to VM

We have a client that any calls going to his extension whether it be via an inbound route, or a direct call from one extension to another, they go directly to voicemail. The message I’m seeing is “DAHDI/1-1”, “MMODE=CHANUNAVAIL”. We are using Polycom phones. The phone log doesn’t even show a missed call, it’s routed directly to unavailable. Anyone ever come accross this and know what might resolve it