Nokia 61xx

Firmware version
*#0000# or *#61x0#
IMEI Code
* # 06 #
Warranty Codes
*#92702689# (= *#war0anty#)

Just scroll down through the information. If entering the above code requires a
further warranty code try entering the following:

6232 (OK) - Month and year of manufacture
7332 (OK) - Last repair date
7832 (OK) - Purchase date (if previously set)
9268 (OK) -Serial number
37832 (OK) - Set purchase date (this can only be done once)
87267 (OK) - Confirm transfer

Enhanced Full Rate (EFR) and Half Rate Mode (HFR)