MOH goes into a LOOP START LINE PORT.
The MOH Out connection on that adapter should look like an RJ11, thus accomodating a regular mounting cord.
To set a line as MUSIC ON HOLD your system has to be IDLE. (No one on the phone)
System Program > Exit/Start > Aux Equip > MUSIC > enter a LINE NUMBER
The LEGEND/MAGIX adapter has MUSIC and BACKGROUND, as well as an RCA plug for input. It also has an adjustment screw. (slotted)
The PARTNER adapter has only MUSIC out, and can not be adjusted.