[dutchbrit]

I haven't tried this out, but I do know it is possible to roughly locate a user via SMS. A lot of government agencies already do this using SMS messaging, basically you can send a silent SMS to a user so they don't even need to 'receive' a message. I assume it works the same way, but not silent(?).

From Wikipedia:

Silent messages, often called “silent sms,” “stealth sms,” or “stealthy pings,” are employed to locate a person or to create a complete movement profile. They do not show up on a display, nor trigger an acoustical signal when received. The mobile provider, often at the behest of the police, will capture data such as subscriber identification IMSI. In Germany in 2010 nearly half a million “silent SMSs” were sent by the federal police, customs, and the secret service Office for Protection of the Constitution.[60]

[cburgdorfer]

Hm, i don't think it works like this, ... ? Must be some other technology... I don't have an iPhone to try, but anyways. I'll figure it out... thanks for the interesting info.