I had already tried the phone directly off of the MDF, no change.

For the time being, it looks like the specific port is corrupt.

The system will not let me copy programming to another extension, as it says the original port is unequipped.

For the time being, I moved the phone from x254/p302 to x241/p121 and renumbered 241 to 254 and programmed as was needed.

Customer doesn't want to replace station module at the moment. Honestly, this is the first problem this system has had in its approx 25 yrs in service.

Thank you all for the suggestions and information. Much appreciated.