Lehman said..
There are no secret codes, only the old known ones:
Check the IMEI
*#06#
Show software version
*#0000#
Enhanced Full Rate Codec (EFR) activation (not S60/S80/S90)
*#3370#
Enhanced Full Rate Codec (EFR) deactivation (not S60/S80/S90)
*#3370*
Half Rate Codec activation (not S60/S80/S90)
*#4720#
Half Rate Codec deactivation (not S60/S80/S90)
*#4720*