There are many mobile phones which come with a locking mechanism that can be used to lock them to a particular network. What this means is that the phone can only be used with a SIM card belonging to that network. If you own a phone that is locked then it can be a problem, especially if you travel abroad. Because the phone is locked, you won't be able to use it with a local network in the country you are traveling to. So you will instead be forced to continue using the original network and pay roaming charges for the service.
If you are an owner of such a phone and you would like to do something about it then you are in luck because you can use it with other networks by unlocking it. You can download unlocker a phone by using what's referred to as Unlock Codes. These codes are unique for every individual handset. The process that needs to be employed for entering this code into the mobile phone varies depending on the brand and model of the phone.
Unlocking is generally considered to be safe as long as the service used to get the unlock code is reliable. Most manufacturers have a security system in place inside the phone that will let you enter a code few times only. The number of tries you are allowed varies from brand to model. However it's usually 3 to 10. If you exceed this limit then the phone will be locked permanently. This is referred to as a 'hard lock'. A phone that has been hard locked can no longer be unlocked using a code. You will need to take it to a service center so that they can unlock your phone manually using specialized equipment.
A phone that has been unlocked once remains unlocked indefinitely. One thing you must take into consideration if you decide to unlock your phone is that in most cases the warranty will be voided. This too will however depend on your network provider's policy.