Inbound calls to an extension route directly to voicemail (Do Not Disturb rule), even though the user is in Available status and the desk phone is not in DND.

In 8x8 Work, set the extension to Do Not Disturb then back to Available.

Sometimes the status shows as Available when the user is still in DND on the back end of the system. Toggling to DND and then back to Available will refresh the status.