:: NOKIA 3310 SECRETS ::  
     
Firmware check
*#682371158412125#

Service codes
*#0000# or *#9999# (Not Tested) 
1st Line - Software Version 
2nd Line - Date of Software release 
3rd Line - Phone Type.

Display the phone's software version.
*#92702689# or *#92772689# 

SIM Clock Stop
*#746025625#

Enhanced Full Rate
For activation enter *#3370# 
For deactivation enter *#3370* 
In both cases the phone will automatically restart. 

Enhanced Full Rate 
Will give you much better sound quality when you enable it. The new Enhanced Full Rate CODEC adopted by GSM uses the ASELP (AlgebraicCode Excitation Linear Prediction) compression technology. This technology allows for much great voice quality in the same number of bits as the older Full Rate CODEC. The older technology was called LPC-RPE (Linear Prediction Coding with Regular Pulse Excitation). Both operate at 13 kilobits.(but you take up more space on the network, so they can charge you more) - Talk-time is reduced with about 5% 
Half Rate
Will give you bad sound quality, which gives the service provider the opportunity to have more calls on the network, and you might get a lower charge from them. - Will give you 30% longer talk-time. 
Half Rate activation and deactivation function is not available with this model.