I'm currently trying to write an app that does, amongst other things, authentication based upon a shared secret principle, using the IMSI (subscriber ID in GSM)

Having had a look at the standard telephony API, it seems that there is a function call called TelSendCommandString. Does anyone have any experience of using this ? I reckon I should be able to use this to send an AT command
(specifically AT+CIMI) to the Wavecom GSM module in the Treo and get the IMSI
that way. Or am I (as we say in England) 'barking up the wrong tree' ?