If you are under contract or on a prepaid cell phone service in the United States, your GSM phone has been locked by the service carrier. Network operators lock phones because this creates a barrier on the phone, which blocks any other services SIM Card from working in your GSM Phone. If your existing phone is locked, you cannot use a SIM card supplied by another network provider without unlocking your phone first. Using a SIM card from that particular country or a roaming SIM card such as the National Geographic Travel SIM is an excellent way to avoid the high roaming rates that US and Canadian carriers charge.
It is a simple process for most United States network operators, but depends on which carrier you go through. When you contact your service provider, most will provide you with an unlocking code (sometimes referred to as a subsidy code) and this may be provided immediately over the phone, or sent to you via email or post.
For AT&T Mobility Contract & Prepaid, this process of issuing the code to you can take up to 7 days and there is no charge. To reach AT&T Mobility Contract and Prepaid, you must call AT&T International Care Toll Free at 1-800-335-4685. However, keep in mind there are restrictions in unlocking your phone. The account must have been active for at least 90 days prior to requesting the phone to be unlocked or the contract period must have ended. You can also call them as there may be exceptions for unlocking your phone. Keep in mind AT&T will not unlock iPhones.
The other main US Provider, T-Mobile Contract & Prepaid, will also provide an unlock code for your phone at no cost. Normally the code is provided over the phone. You can reach T-Mobile by calling 1-800 937 8997. Your account must be active for at least 90 days prior to requesting the phone to be unlocked. However, if you show proof of purchase through a faxed document, T-Mobile may unlock a phone if you paid full retail price.
In Canada, there are no laws regulating SIM locking or unlocking. No Canadian wireless service provider sells unlocked phones. Yet, as per the Cell Phone Freedom Act, introduced by Parliament June 2010, carriers are prohibited from selling SIM locked phones in Canada without first informing the consumer of the existence of such a lock. Additionally, there are laws mandating that phone companies selling new phones must unlock customer phones, without charge, at the end of contract or upon purchase of the phone outright, when requested by the customer. Each company has its own set of stipulations
If you are unable to get your phone unlocked from your provider there are paid unlocking services available. We recommend gsmliberty.net. Unlocking codes are available within 24 hours and prices start from just $6.99. Visit their website to find out if they can provide your phone with an unlock code. We also recommend www.unlockscodes.com as a provider for unlocking codes.