You may have heard the term " blocked" or "blacklisted" when referring to a phone that is unable to connect to the network. While on the surface it may seem like that would be the same thing as a network lock, it is extremely important that customers understand that it is in fact very different.
A network lock is (sometimes) added to a phone at the factory when it is manufactured. The network lock restricts the phone such that it can only be used on a specific network or within a specific region. All the functionality related to the network lock and the process of unlocking it is built into the phone.
If a customer tries to use a network locked Samsung or BlackBerry on a different network, they will be prompted to enter an unlock code. Once the code is successfully entered, the phone will be unlocked and capable of being used on any GSM network worldwide.
No phone is ever blacklisted by default. A phone will only be blacklisted under a special set of circumstances e.g.
- The phone is reported as lost or stolen
- The phone is reported as stolen
- The customer is under contract but has gone x number of weeks without paying their bill
Blacklisting blocks the phone at the network/carrier level not on the phone itself. IMEI blacklists are shared across different carriers in a given country (and sometimes across countries) to prevent users from just moving to another network. Since blacklisting operates at the carrier level, it supersedes unlocking. You must contact the phone's original carrier to be removed from the blacklist.
Implications for customers
- Even if you unlock your phone, you must bear in mind that unlocking does not remove your contractual obligations. If you have a contract and you do not pay your bill before leaving your carrier, they might blacklist your phone at some point in the future.
- If your phone is already blacklisted, unlocking it probably still won’t allow you to use it on a different carrier. If the phone has been barred/blacklisted in the US for example it will not work on any US/UK/CA network and it may not work on some other networks around the world depending on whether or not they share blacklist information.
Customers who buy phones from third parties or online sites like Craigslist should be very wary of the fact that a phone may be blacklisted. Here are two websites that you can use to check if a phone is blacklisted based on the IMEI number (Dial *#06# to find your IMEI):