Iphone is locked to orange will it work on other network if its unlocked?

My iphone 4 has been locked so i can't use the data from orange but i'm refusing to pay for their services as i have complained to them that the signal keeps cutting off and wanted to terminate my contract.anyone know if i unlock my phone will it work with other sim cards except for orange?

Added (1). Sorry guys i forgot to mention its a contract phone and its overdue thats why its locked and its on orange. Will other sim cards work if i unlock it?

Yes, that's the entire purpose of unlocking.

Yes that is the whole point of unlocking. Make sure you get it factory unlocked to stop it being locked back to orange after any software updates or after you connect it to your iTunes account on your lap top / pc

You must jilbrek it and install cydia.

this video can help you:

Yes temporarily!

Orange if you do NOT pay will BLOCK the phone on All networks

ALL NETWORKS CAN BLOCK A PHONE, IT PREVENTS PEOPLE STARTING A CONTRACT ON ONE NETWORK AND "RUNNING" OFF TO ANOTHER… INTENTIONALLY

Your phone use will be limited, and it can only be unblocked by Orange only after all arrears are paid and by that time the debt collectors will be a knocking

@15.10 01/12/12/ re Additional Details
Yes TEMPORARILY! You may already be getting letter from Orange re further action

Yes, if unlocked it will work on other networks. For the record it is locked even if you are paying on time. The phones are sold locked to their respective carriers for the length of the contract.

Yes it will work. Just call them to unlock the handset, they will charge you £15. You are still liable to pay your phone bills until the end of the contract term.