Don't know if your W140 is the same as mine (I have a '96 S500). Its set up for the keypad behind a pop-up panel in the dash and the rest of the phone in the console.
Anyway, mine came without the phone option, although its got all the wiring, etc.
Behind my pop-up panel is a small velour lined box, like a small glove compartment. The rear is a false panel of sorts held in with two screws. The back of this panel holds the ends of the wiring connectors for the phone. I guess they all cam "pre-wired".
This is a really handy place to put your sunglasses, garage door opener, etc.
In the console, the space normally used for the phone is replaced with a piece that has two cup holders, etc.
Anyway, if you can find a W140 without the factory phone in a salvage yard, you can get these pieces and add some useful space in your car.
Its too bad nobody seems to make a digital system to replace the analogs in these cars... at least, I've never seen one.
KenP