Most mobile phones are linked to a particular network such as Virgin, Vodafone, O2 or EE. This means that the phone is locked to that network and will not work with any others.
Network operators are allowed to lock your phone because they often subsidise the cost of phones when you take out a contract, so want to make this money back before you switch to another phone company.
Unlocking your phone means you can use it on any network you like.
Unlocking your phone may sound like a no-brainer, but that disadvantages as well as advantages to consider.
You may be able to get benefit from cheaper tariffs
You can take advantage of any network-specific deals
If you sell your phone it will be worth more if it is unlocked
It may invalidate the warranty, so you may need to consider insurance if your phone is expensive
It will usually cost you to unlock your phone
Start by calling your existing network and letting them know you want to unlock your phone. Each network has different rules on when you can unlock your phone, how much they will charge you and how long the process will take.
Some networks will unlock your phone for free, so check the tool on the Ofcom website to find out your network's policy. Some networks charge up to £20.
You will probably need the following information when you call:
Your mobile number
Your manufacturer and model number (which can be found on the outer case of your phone)
Your IMEI number (a serial number which can be found by typing *#06# into your phone)
Your provider will then give you an unlocking code. When you have this, you can put your new provider's SIM card into your phone and enter the code. It will then display a message to let you know it has worked.
If you have an iPhone and need network specific instructions, read our guide to find out your options.
If your network charges you to unlock your phone, it is worth seeing if you can get it done cheaper elsewhere. Some phones can even be unlocked for free using a code you can find yourself on the internet.
However, it is worth noting that not every kind of handset will be covered and you may not be able to find a code for your phone.
You can find out if a free unlock code is available for your phone or get a range of quotes for a paid unlocking service using the Unlockapedia on Giffgaff's website. Compare the price of each service and how long it will take to what your network quoted you.
You can also pay a fee of around £10 to get your phone unlocked on the high street, either at an outlet dedicated to this service or at your local phone shop, but it is worth shopping around to get the best deal.
Some will do this with a code, like the online services, and you may feel that being ripped off is less likely in person. Others will handle the process manually, using a cable to attach it to a computer and some specialist software.
You can also buy the equipment to manually unlock your phone yourself online, although it is only worth considering if you are confident in your abilities in tinkering with technology!
If you are thinking of unlocking your phone it is worth making sure that the fee you pay to unlock it will be outweighed by savings you will make by having the freedom to switch networks, otherwise it may be best simply to stick with your current network. You could always try to haggle your way to a better deal.