Zoom Dial In says "This Meeting Does Not Allow Phone Dial In"

We were running Zoom Video meetings and a few of our participants would use the Zoom Dial in number to access via phone because they did not have access to video.  When they would dial in they would be asked for 1) Zoom Meeting ID# 2) Participant ID 3) the meeting passcode. 

This feature worked seamlessly for our phone participants for over a year. Recently this all came to an end. Now when they dial in they enter the meeting ID (Which has not changed) and receive this message..."This Meeting Does Not Allow Phone Dial In" and then the line disconnects.

Nothing has changed on the admin side. All settings have been the same for over a year.

Any suggestions on what may have changed to cause this?