*#92702689# takes you to a secret menu with 6 choices:
[*#war0anty#]
1. Displays Serial Number.
2. Displays the Month and Year of Manufacture (0997).
3. Displays (if there) the date where the phone was purchased (MMYY).
4. Displays the date of the last repairment - if found (0000).
5. Makes you capable of transferring user data if you have the gear for it.
6. Shows how long the phone has been used to talk. This counter is not reset by when you "clear timers" like the counters in the call register.