If anyone can find or give me a standard cable schematic for a 3310 MBUS cable it would be helpful.
I don't think it has a chip or anything like that, it's just a little black box (that goes into the phone) which has inside it a little switch marked F and M and the end of the wire from the serial plug (3 wires). Two of the pins that connect to the phone are soldered together. As for the serial plug I don't know what is in it as it's moulded.

thanx

Rob