E39 touring, location of GSM module

I've just bought a 523i touring with a GSM phone between the seats - unfortunately the SIM card reader between the seats cannot read newer SIM cards, and rumors on the internet says that the GSM module itself has a reader that can. On the E39 sedans the GSM module is said to be located in the left part of the trunk -- but noone seems to know where the module is located in the touring version. Can anyone help me?