Your Nokia 3310 can be unlocked from its current network provider using an unlock code generated specifically for the handset. There are websites that offer unlock code generator tools for several Nokia cell phone models, including the Nokia 3310. Basically, you provide the unlock code generator with your handset's IMEI number, and the code generator generates a couple of codes for the handset.
Go to a website like GSM/Unlock, Peters 1 or Unlock Nokia Free.
Enter your Nokia 3310s IMEI number on the website. To find out the IMEI number of your Nokia 3310, type "*#06#".
Specify the network carrier the phone is currently locked to, for instance, T-mobile or AT&T.
Wait for the website to generate the codes, which should take just a few seconds. The website will then create seven or eight unlock codes for your Nokia 3310.
Turn on your Nokia 3310 without a SIM card and type "#PW+CODE+1#". This code can be any of the codes provided by the unlock code generator. If you don't see the message "SIM Restriction Off", try another code.
Don't try more than five inaccurate codes or your phone will be permanently locked. If none of the free codes is accepted by your cell phone, contact your network provider and ask for the unlock code.