نوكيا

Nokia 6110 - 6150

*3370# to activate Enhanced Full Rate Mode
[Call quality increases, battery life decreases!]

Newer versions of the phone software (probably from version 4.73 onwards, if I'm wrong someone correct me!) have got EFR activated as standard, so *3370# doesn't work. MTN South Africa supports this feature.

#3370# to deactivate Enhanced Full Rate Mode

Note:
After pressing these codes the phone will shut down and start up again with the service activated/deactivated.

Nokia 5110 - 5150

IEMI
If you need to know the IMEI code of your phone, simply press:

* # 06 #

...and you'll read it on the LCD display

To get additional information from your phone you can use the so called "warranty code", try typing:

*#92702689#    (= *#war0anty#).

Now you are in service menu where you'll find:

1 IMEI (International Mobile Equipment Identification)
2 Made MM/YY (date of production of the phone mm/yy)
3 Purchasing Date (here you can enter the date of purchase. If you enter an incorrect date, you cannot correct it later !
4 Repaired (date of repair, if there was one)
5 Transfer user data?

*3370# EFR will be activated after a reboot of the phone ( consumes more power )

#3370# EFR will be switched off after a reboot of the phone.

*4720# Half Rate coded will be activated after a reboot of the phone ( better standby time )

#4720# Half Rate coded will be de-activated after a reboot of the phone

If you press the "Power on" button for a short moment, the menu with the profiles is shown on the display. 

If you press one more time, the mobile turns itself off.

You can use the up and down cursor keys to scroll and enable a different alert setting.