Unlocking your phone means you can use any network's Sim card, giving you the freedom to switch providers, lower costs and pass on your phone to others.
This is a step-by-step guide to freeing your mobile from its digital shackle, covering all the methods available.
In this guide
Why unlock your phone?
When you buy a new phone, chances are it'll be locked to the network you bought it on - and if you try to put another network's Sim card in, it simply won't work. Unlocking it means you can use the phone with any compatible Sim card, on any network. This has several benefits:
Bag a cheaper tariff
If you're happy with your phone handset, but don't have a good deal, unlocking it allows you to keep the phone but switch to another network. See Cheap Mobiles for more info on switching.
Grab promotional deals
Often networks give away free Sim cards, which can come with free texts or calls. Yet if your phone isn't unlocked, you can't put them in and take advantage. Any decent free Sim offers are included in the free weekly MoneySaving email.
Added handset value
Unlocked phones tend to sell for more on websites such as eBay, because they have much wider appeal to users on other networks and in other countries. Check our eBay selling tricks guide for more information.
Freedom to roam
Unlocking means you can use foreign Sim cards to cut phone costs while you're abroad. See Cheap Roaming for more.
In short, unlocking gives your mobile independence from the network you got it from - and it's usually simple to do. Many older handsets can be unlocked using codes generated free on the web, and if that doesn't work, you can do it for a reasonable fee, either through your network, or high street phone unlockers.
Even if you have to pay your network to unlock the handset, unless you're on a particularly good tariff already, the savings should quickly outweigh the outlay.
Why do mobile phone companies lock phones?
Mobile companies say their phones are already heavily subsidised to entice you to buy them, and they need to make up this shortfall. Yet the reality, as ever, comes down to cold hard cash. For the firms, it wouldn't make sense to sell you the phone at reduced cost, and then let you take your cash to another network provider.
However, it's not all doom and gloom and some providers, such as Three, have started selling unlocked phones - both to those on pay-as-you-go and pay-monthly contracts.
If you want more info, Ofcom has produced a table detailing the costs of unlocking for each network and the average time it takes.
It's perfectly legal to unlock your phone
It's a common misconception that unlocking your phone is illegal. Unsurprisingly, mobile phone companies aren't keen to dispel this myth. The confusion arises because unlocking and unblocking are often mixed up. They mean different things. In a nutshell:
Unlocking is totally legal
It just means making the phone work with any Sim card.
Unblocking is illegal
This is the practice of making a phone work again after it's been blocked by the networks, usually as a result of its being reported lost or stolen. It's thoroughly illegal and should not be attempted.
What about my warranty?
While it's not illegal, unlocking your phone WILL invalidate its warranty in most cases. So make sure you think twice if you're still in the warranty period and have a super-expensive handset. While it's possible to 're-lock' some phones, you shouldn't rely on this.
Is there any way around it?
It's possible to get a Sim unlocking attachment. It's a little device roughly the same size and shape as a Sim card, which goes in the handset's card slot alongside the Sim itself.
Effectively, the device unlocks your Sim to make it work with the handset, rather than the other way around, so your phone warranty remains intact when you use one - though obviously you can't sell the phone as 'unlocked', because it isn't.
Whilst these claim to unlock most handsets, feedback has been patchy so far. If you've used one, please report your experiences in the Mobile Unlocking discussion.
Get Martin's Free Money Tips Email!
For all the latest deals, guides and loopholes - join the 9m who get it. Don't miss out
How to unlock your phone
Before getting down to it, have you tried putting a different Sim in your phone to see if it works? If you have and it doesn't work, there are two distinct ways to unlock mobiles:
Using a code
This is known as 'remote unlocking' and involves getting and entering a special code into your phone, which gets rid of all the restrictions as if by magic, and is by far the most common method.
Using a clip and cable
This involves unlocking the phone using a specific data cable and software, and applies to a limited number of handsets. Most people will send their phone to a dedicated unlocker for this service. It's possible to do it yourself if you've the technical nous, but this can be time-consuming and complex.
Method 1. Check if you can unlock your phone for free
Several sites simply list codes for a range of older phones without charge. Many people believe the practice of locking phones is anti-competitive, and so there's a lot of info to help consumers fight back against it. If you've a newer phone, it's likely there won't be a free code available - yet there's still no harm in checking before you move on to paid options.
The free method works best for older phones. Giffgaff's useful Unlockapedia notes that while this method works for many old Nokias, LGs, Panasonic and Siemens phones, it's unlikely to work for most others. It's still worth quickly trying to see if you can find a code for your phone just in case, though after trying that, go to Method 2.
Step 1. Get your facts right
To find a working unlocking code for your handset, you need three pieces of info: its brand/model number, the network, and the IMEI code. Here's how to find them.
Brand and model number
The chances are you already know this, as it's likely to be written on the handset, its box, and any documentation you got when you bought it, so we'll move on.
This is simply the network the phone's currently locked to, not the one you want to get on.
The International Mobile Equipment Identity is a unique number given to all mobile phones, which gets marked as invalid when phones are reported lost or stolen. To find your IMEI, simply type *#06# into your handset, and note down the number that appears.
Step 2. Find an unlocking code
There are a raft of websites dedicated to phone unlocking. Which you should use depends on your handset brand.
The easiest way to unlock older Nokias is via codes found on sites like Unlock NokiaFree.
Try Giffgaff's handy Unlockapedia - just pop in your handset type to get more info. You'll find a full discussion of other phones in the Unlocking non-Nokia phones discussion in the Mobile Phone Forum. If you can't unlock your phone with a free code, go to Method 2.
Step 3. Use it!
The sites above will generate a code based on the info you provided, so double-check it's right first. The code will look something like this. #pw+2746763089+1# (Nokia phones), or *2767*637# (other makes).
To unlock the handset, take the Sim card out of the phone and put in a different network's Sim. Now you can put the code in.
How to enter the code
This can be fiddly - for some phones, rather than using the regular text keys you need to use the * key if you want to produce letters as opposed to numbers. For example, to produce a ‘p', press the * button three times within two seconds; to produce a ‘w', press the * button four times within two seconds; to produce a ‘+', press the * button twice within two seconds.
You should now get a message saying ‘phone restriction off' (or words to that effect). You generally only have five attempts to enter the correct code so be extremely careful. If none are successful, the phone will still work, but you'll have to go to the network or a retailer to get it unlocked instead.
Method 2. Buy a code
If you haven't found a free code, it may be possible to buy one. Obviously the aim here is to find the code as cheaply (and safely) as possible. So it's only worth doing if the reason you're going to unlock your phone will save you more than the cost of unlocking it.
This applies to most modern handsets too, so it's worth trying, but if it doesn't work then there's still a chance using Method 3.
First, get a quote from your network
Call your current network to ask it how much it'll charge for an unlock code. In the past, networks have tended to play fast and loose with unlocking fees, to the extent it often seemed they're making them up as they go along. These can vary widely depending on your handset and network, though some offer it for about £15-£20.
Then, try the dedicated unlockers
Having got a benchmark unlocking price from your network, you can hit the high street and web to see if they'll beat it.
While the web's probably not the best place to look due to the amount of dodgy operators promising quick fixes, it's likely there are businesses offering mobile unlocking on your local high street. Check phone shops, markets and even some newsagents and key-cutters - they might be cheaper.
The added advantage of these is that if they can't do the job you won't be charged (always check though), whereas on the web you may pay regardless.
If you're looking online, be sure you know exactly what you're getting before you pay. Read the terms and conditions to make sure they won't fob you off with something other than the code you need. Also, always check the site's legitimacy, as sadly there are some dodgy operators out there.
Do note, while some are much quicker and can send the code in fifteen minutes, some report it can take several weeks for your code to come through, depending on the network. Once it arrives, follow the instructions in method 1 to put it into the handset.
Important note: If your network can't quote you a price for an unlock code, then it may mean your phone isn't unlockable by code (they should tell you this if asked). If that's the case, don't bother looking at other sites that sell codes - they may charge you just to tell you it isn't possible. Go straight to method 3 instead.
Used online unlocking services?
Please report good/bad feedback in the discussion: Mobile Unlocking
Method 3. Unlock via a cable
If all else fails, your phone may only be unlockable by using a cable attachment. You can either pay to have it unlocked this way, or, if you've a keen head for technology, do it yourself.
Use a high street or market unlocking service
Since you're going to have to post your phone to any online unlocking service for them to be able to unlock it via cable (a process which can in itself be costly and cause headaches) the local unlockers have the upper hand.
It's worth asking for a few quotes and playing the sellers against each other. With these sorts of services, you may be surprised at how far a bit of haggling can go.
Do it yourself
If you fancy yourself as a tech-nerd, you can also buy a cable on eBay or via cheap accessory websites, and download free software which should do the trick.
An important warning: this can get complicated, so be sure to research it thoroughly online before parting with cash for the unlocking 'clip'. Be very careful, as this method is only for the technologically experienced who can work through all issues.
There are different clips for each brand, and often for different handsets within that brand, so make sure you get the right one for your needs. If you only want to unlock one handset, then the most economical option may be to buy the clip, unlock the phone, and then re-sell it on eBay to recoup your costs.
Now it's unlocked, go and save some cash!
Now your handset's unlocked, the mobile world's your oyster! Read the Cheap Mobiles guide for info on getting a good deal, and Cheap Mobile Roaming for top deals on calling from abroad. Also, check out the Orange 2for1 Cinema article.
If you've tried everything above to no avail, and you're left with a handset you don't want and can't unlock, why not recycle it to earn some cash. To help, use the MobileValuer tool to instantly find the top payer for your phone.