SIM Card Protocols

Just how does a cell phone or card reader communicate to a SIM? Its does by passing it commands via Transport Protocol Data Units (TPDU) and Application Protocols Data Units (APDU).

 Here is a white paper that dicusses these units and how they provide communication with smart cards (and by inheritance SIMS).

SIM Card Protocols 

I hope this is of some use to the community.

Mike