Don't confuse the ctx with the 616. The protege 616 is the small 3x8 with a 3x8 exspansion. There is alot of confusion about the progression of what used to be labeled the digital 616 mat code 431484(looks like a ctx) the older software ran the old type phones starting with ko8uso software they ran the new phones. They changed the control board and software to make the ctx. I am going to start a new thread about these older units as sprint does not support them any longer.