I suspect that their satellite phone sends enough information in "headers" to the satellite (during a call), that intel would know the make, model and S/N of the phone. From that, it would be possible to track down who al-Qa'ida's favorite supplier is, break into his shop late at night, and add about three ounces of C4 to the model most popular with those dirt bags. Like the add says: Reach out and touch someone!
--Boot Hill
I remember reading a story posted here back in February/March that was about a Swiss company [the name slips me] that sold satphones that were supposedly anonymous. They were a favorite of the terrorists. The gist of the story was that the spooks somehow got a way to make some id's and that was a major step in catching KSM. I do recall the "source" of the story saying that AQ caught on to what was happening, and radically curtailed use of the phones, so revealing the "secret" was considered no problem.