I wanted to display this phone in a prominent location but didn't want to cut a hole in the wall which would have been difficult to repair if we move or I change my mind. So we had our handyman construct this oak frame which sticks out from the wall giving enough depth for the phone's components.
The red oak box-frame is 2 inches deep and is held in place by 4 angle brackets which are screwed into the wall. If I decide to remove the phone it will only leave 4 screw holes to repair. The plywood inserts are glued and stapled to the back of the frame lip. Each insert has a #10-24, T-Nut stapled to the back which the phone is screwed into using 1-¼" flat head machine screws.
Note to collectors: to remove the mat retainer frame (bezel), grasp mat retainer frame at top, lift upward and out to release frame from panel of set.