Knowing how you use your phone and choosing the right package is key to ensuring you get the best value from your mobile phone deal.
Going over your call allowance, phoning certain numbers that your allowance doesn't cover, or using too much data can all lead to you paying more than you expected.
Similarly, having a monthly allowance of thousands of free minutes and texts may seem like a good idea at the time, but if you don't use them you could be better off choosing a cheaper tariff with a reduced allowance.
Look at your last couple of bills to work out your normal usage, or ask your provider to give you a breakdown. It may have an online account facility where you can access this information.
Price comparison websites, accredited by Ofcom, can also quickly analyse your past usage and can then search the best deals that match it. You can find those that compare mobile via our price comparison page.
With a pay-as-you-go (PAYG) deal you pay for services in advance by topping up your phone with credit.
These deals can be particularly useful for people who don't make many calls or want to keep tighter control over their bills as you only pay for what you use. You can also change or end your deal at any time.
However, the cost of calls may be higher than on contracts and downloading may also be more expensive so it's a good idea to shop around and compare the various deals on offer.
You'll also have to buy a handset and you'll probably need to top up your phone, make a call or send a text once every few months (usually at a minimum once every six months) as mobile companies may suspend PAYG services and recycle the number if they think they're not being used.
With a contract you agree to pay a regular monthly fee (eg: £25) for a set period (12, 18 or 24 months).
In return you typically get a handset and an allowance of inclusive minutes, texts and data each month (for example, 200 minutes of calls, 1000 texts and 500MB of data.)
This type of deal can be good choice if you want a newly released smartphone without having to pay a large fee up-front. See Ofcom's proposals to ensure fairer, more transparent prices for mobile customers who pay for handsets and airtime within the same contract.
Before signing up, check if the allowance covers the type of calls you make if you make a lot of calls to certain numbers not covered (calls to numbers beginning with 08 or to international numbers are often not included), consider buying a special add-on bundle that does cover them to avoid lots of additional charges.
Make sure you know how much it will cost if you exceed your allowance of calls, texts and data. Some providers charge a lot if you go over your monthly usage limit.
If you already have a phone and just want a monthly allowance of calls and texts, this could be the deal for you.
You get a new SIM card, or you can use your existing SIM but with no new handset.
You can choose one-month or 12-month plans, and they include a monthly allowance of calls, texts and data.
They're often cheaper than a contract with an inclusive handset; a number of tariffs are lower than £10 a month.
You can also get SIM-only PAYG deals.
If you're worried about going over your allowance, speak to your provider to ask if you can set a 'cap' or 'limit' on your account, which will stop you spending over a certain level. Ask your provider how it works, as some limitations may apply; e.g. some caps might not cover you when you use your phone abroad.
You can monitor your usage from your phone if you have a smartphone, by using a free-to-download app from your provider. These can be very useful for checking how much data you're using and how many texts you've sent. Apps can also count voice minutes used but they might not be able to work out which minutes would be included in your allowance and which you would be charged for.
Most phone companies also offer an online account where you can check what you have used, which can be accessed from your phone or computer.
Even if some or all parts of your allowance are 'unlimited', it’s still worth keeping tabs on your use, especially if there's a 'fair usage' policy which restricts what you can do.
If you have a smartphone or a mobile-enabled tablet you can save your data allowance by using Wi-Fi, either Wi-Fi hotspots or your own home Wi-Fi, to connect to the web.
Some smartphone settings and apps can seek out Wi-Fi networks and prompt you to connect to them so that you don’t have to do this manually.
Using your phone overseas (roaming) can cost considerably more than it does at home, particularly if you want to surf the web a lot, upload photos to social networking sites or check or send lots of emails.
You can even run up a big bill without actively using your phone, as smartphones and 3G/4G enabled tablets automatically seek out mobile connections and use them to update apps.
So unless you turn off data roaming before you go, these devices could be downloading data at standard rates throughout your stay without your realising it.
This Ofcom guide explains more about using your phone abroad - including how to switch off data roaming - so that you can avoid running up a large mobile bill.