Firstly, i do not use iPhone, but i had a tenant who used iPhone 'fan'.
One day, my ex-tenant (say, girl) had a called from her friend.
Her friend asked her where she was, and she said she was in town.
But her friend said he knew she was at home, as he had set the iPhone by location.
This meaning that in iPhone, if the User set to locate where the iPhone is, it can be trace by another phone.
Another example, in STOMP
The Stomper (say, he) had lost his iPhone.
When the thief switch ON the iPhone, it automatically took a picture, front camera, of the thief, and sent a picture to the User.
Then he sent the message to the thief that he had the picture on the thief, asking the thief to return, else he will report.
So, basically most of the iPhone security features can be set by the User.
The telco can only deactivate the SIM card.
When told by the Court to trace the location of the mobile, the telco may able to trace.
If you buy or sell the mobile handset, the dealer need your NRIC & the mobile handset imei, to make a record on the book.
This is required by law (i think) is for the Law Enforcer (Police) to check for any stolen mobile handset (reported).
Edit:
It is up to the User to lock by SIM card.
Telco not allow to lock mobile handset. IDA policy.
