Has anyone tried these dial pad codes for EFR?

[rdifiori]

*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)

 

[Thuoudo]

Is this...like...safe? I know you can dig into the settings to change the max volume of the earpiece on Samsungs, but it's not recommended.

The ear speaker quality on my 900 is terrible But since I don't use much voice, 5% less talk time is a hit I'd be willing to take.

 

[Thuoudo]

Ok, looking around the net, it's in all likelihood that the 900 is already using EFR.

It gives an "Unexpected Data Value" message when you try it, anyway.