Sony Ericsson

Find Secret Games: Snake on the sony ericsson T68 – Go to Erix and then on the main screen press 123 and you will be taken to the snake game.
For Most of the Sony Ericsson Phones(all most all models).

Service Menu – >*<<*<* This code will show you hidden system items.
Silent Mode – “#” or “C” Puts the phone in silent mode or disables it.

Phone Status – Press Volume Key In Stand-By mode “This will show your phone status”

Quick Menu – “C” in Stand-By Shows up the smal menu with options: Silent, Profiles and IR.
Stay tuned as i will be posting more tips & tricks about sony ericsson phones specific to various new models available with sony erricsson.
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Nokia

*3370# >> It activates Enhanced Full Rate Codec (EFR).
#3370# >> Deactivate Enhanced Full Rate Codec (EFR).
*#9999# >> check nokia phone software version if *#0000# does not work.
*#2640# >> Displays the current phone security code.
*#30# >> Lets you see the private number.
*#06# >> For checking the International Mobile Equipment Identity in short imei no.
press and hold # >> switch between lines 1 and 2.
*#7780# >> Restore factory settings