The pre-facelift (i.e no indicators in mirrors) ML did not support the 6310. it was either the 6150/6110 version, or if it had the clip at top of cradle that physically holds the 6210 in place, the 6210 version. The 6310 version came in in about June 02. UHI was added to ML in MY2004.
The facelift ML has the phone controller under driver's seat - I don't know where older ones had it - if it is under drivers seat, see if you can read the part number and post it here ...
R