Unlocking of phones is required if you wish to switch your SIM to some other network while retaining your phone. Nokia phones are easiest, while LG, Moto are sometimes extremely difficult. If you are happy with your network, forget about unlocking. Also beware of various unlocking companies and individuals. It is difficult to find trustworthy ones. On ebay many times people sell locked phones by posting them unlock. You need a lot of luck if you intend to buy an "unlocked" phone from ebay.