This is a tip for anyone who bought the Samsung E2120 from O2 recently for £15, and wants to unlock it:http://www.hotukdeals.com/item/599444/samsung-e2120-mobile-phone-15-02-wa
This unlocking offers a temporary unlock until you remove the SIM card, in which case you have to do it again.
***WARNING THIS WILL FULLY RESET THE PHONE MEMORY AND YOU WILL LOSE ALL CONTACTS, TEXTS ETC!***
1. Turn mobile phone on with unaccepted SIM BUT NOT FULLY INSERTED
Dont put the battery in fully, but enough to make contact for power.Switch on phone and wait for it to say no sim inserted, then use a thin implement [such as a 15cm ruler] to push the SIM all the way in.
2. Input *2767*3855# and phone will reboot and will be temporarily unlocked.
As long as you don't switch the phone off the unlock will continue to work.
I tried this with a t-mobile SIM and this worked perfectly.
All credit goes to g_p_t for his helpful post:http://www.hotukdeals.com/item/599444/samsung-e2120-mobile-phone-15-02-wa/showpost.php?p=7856206&postcount=74