I think that's a pretty extravagant present. I'd check with his mother, she may have no idea how much it's worth

OT: Yes all phones have an IMEI (equipment identification number) and the SIM has an IMSI which is the subscriber identification.

Everytime you make a mobile call (on telstras network at least) it can check your sim against the handset and record it, so it knows when you change sim cards between phones etc.