Activate some hidden Nokia mobile phone features

Link: Bulletproof Productions: Nokia Mobile Phone Hidden Features.
This caught my attention whilst I was looking through Serkan’s blog this afternoon.

These codes will work on most Nokia Mobile Phones to activate/deactivate advanced hidden functions that you can’t change through the phone menu
Code Function
*3370# Activate Enhanced Full Rate Codec (EFR) – Your phone uses the best sound quality but talk time is reduced my approx. 5%
#3370# Deactivate Enhanced Full Rate Codec (EFR)*#4720# Activate Half Rate Codec – Your phone uses a lower quality sound but you should gain approx 30% more Talk Time
*#4720# Deactivate Half Rate Codec

There’s a heck of a lot more! I haven’t tried’em – it’s a useful reference of commands.