There are basically two types of network systems that exist for mobile phones. The CDMA network is basically a response mechanism that links one cell phone and its user along with a number. This system is used mainly in the US as well as a few other countries around the world. The other type of network is known as a GSM network that stands for Global System for Mobile Communication. This type of network is the preferred network for international use and it is also becoming more prevalent in the United States, the UK, Australia and Japan.

Among the many benefits of GSM mobile phones is that they predominately use SIM cards that are removable. This allows subscribers to transfer their important phone data seamlessly from one phone to another. GSM mobile network providers can unlock and lock mobile phones so that SIM cards from different networks cannot be used on certain phones. Most of the time, this is because of the competitive landscape of mobile phone providers. However, in this present day of fast-moving technology, it is quite easy to unlock almost any type of mobile phone. Once the phone is unlocked, the mobile phone's owner will be able to remove their SIM card from one phone and immediately use all of its information in another unlocked GSM mobile phone. This allows for unparalleled convenience when it comes to business travel and avoiding roaming charges, especially in international countries.

Many mobile phone owners do not know how to unlock a cell phone so here is a quick tutorial. The first step in unlocking your GSM mobile phone is to determine what type of service your phone runs on. If the phone is a CDMA phone it will not have a removable SIM card, so there won't be any need to unlock it. Once you determine if your phone is of the GSM variety, you need to know whether it is unlocked or not. The easiest way to do this is to borrow or purchase another SIM card that is from another service provider and see if it works in your mobile phone. If your phone begins to operate by sending and receiving calls with this new SIM card installed then it is not locked. If your mobile phone has been locked by your service provider then you will not be able to make or receive calls using the SIM card from an alternate network.

Next, you should go to the Internet to find a company that is willing to provide unlocking codes for your particular phone, network and provider. There are a plethora of companies that charge a range of fees for unlocking your mobile GSM phone. Some of the variables that are more important are the price of the unlocking service, the reputation of the company, whether or not your particular mobile phone model can be unlocked or not, and the delivery times that these unlocking services promise. In rare cases, the model of phone that you have may need to be sent in to a hardware specialist that can connect the GSM mobile phone directly via a USB cable. This tends to only happen with phones that are significantly out of date. There is also the option of purchasing the necessary hardware and software to unlock the phone yourself.