Thank's...

Ignoring GSM modules, and instead looking at GSM phones complete with a subscription, you can get the GSM phone for free, i.e. zero initial cost. The reason is that it is sold bound to a specific subscription. Do you really want to set out embedded equpment bound to a subscription? What would the total subscription cost be for a 10-year period? What service would the phone give if the user happens to forget to pay to prolong the subscription? What would be the administrative costs of keeping track of 1 or 10 or 100 or maybe even 1000 subscriptions?

At least the SIM card communicated with BTS.Then able to received the "time clock GSM network" even the SIM no longer have credit pulse nor subscription(menas others SIM cards).

BTW...Mahmmod projects..

Thank you
Jeckson S Ben