[thstone]

You will need a SIM card for a GSM compatible network AND the optional phone kit installed from the dealer.

My understanding is that all cars have the SIM slot but it won't work without the optional phone kit. The info that I have says the option is code 666 - Phone Option for PCM or PCM2 Telephone (GSM). If installed, the "666" code should be on the options list on the decal under the front trunk lid.