If you're happy with the phone you've currently got, or have inherited one from a friend or relative, then you could be much better off choosing a SIM-only plan. Plenty of UK customers get a 24 month phone contract and then keep paying the same monthly cost long after that initial term has finished. Is that you? Then good news - there's a fair chance you could save by switching to a SIM-only plan, even if you stay with the same network.
We like these pay-monthly SIM-only deals, because they're great value and give you more for your money than a pay-as-you-go plan. There are 1-month, 12-month, and 24-month plans - and even more over on our mobile site. But first let's take a look at the best of the best.
Plusnet Mobile offers this perfectly balanced plan that gives you a decent bit of data each month, unlimited texts, and unlimited minutes for a great value price. It's perfect if you prefer to chat on the phone than use web-based services like WhatsApp. Plus, you'll get access to extra discounts if you've already got Plusnet broadband at home, not to mention the provider's award-winning customer service.
Our selection if you fancy a deal with a freebie is with BT Mobile (www.BT.com). All of BT's SIM only plans come with free BT Sport via the BT Sport Lite app. Considering how much premium sports channels can cost, this really is a great offer - it's one of the cheapest way to get BT Sport, in fact. OK, so you don't get it on your TV, but with the app available on both iOS and Android, you can stream and watch live sport on your iPhone, iPad or Android device.
Remember that streaming TV and video on any device uses up internet bandwidth. If you're not connected to Wi-Fi then using the BT Sport app could use up a lot of your data allowance. We reckon streaming a 90 minute game would use up around 1GB of data, which is why we recommend this plan.
This deal from Carphone Warehouse's resident network, iD, has got a bit of everything: a nice chunk of 4G data, plenty of texts to see you through the month, and a bargain price tag. 30-day terms mean you can always switch your tariff around whenever you want, and because it's one of iD's 'Shockproof' plans, there's an automatic cap to stop you spending too much over your monthly allowance.
Three's data plan is probably the best deal you'll find if you regularly watch videos, stream music, play online games, or donwload apps whilst you're out and about. Besides, we're fans of Three - it's got good network reliability and speedy 4G included at no extra cost. You can also get a Micro SIM or a Standard SIM
The fantastic thing about this deal from Sky Mobile is that whatever data allowance you pick, you can change it whenever you want - whether you find you need 1GB, 3GB, or 5GB. Texts and calling minutes will cost extra, but you can get an unlimited allowance added on at no extra charge if you've got Sky TV.
Talkmobile is offering loads of data, at a value for money on its XLarge SIM-only plan. That's perfect if you're on a budget but still want to listen to Spotify on your commute. The great thing about Talkmobile is that you'll always get good value, and with a plan like this, it's straightforward and simple to understand.
This EE SIM only plan is a great choice if you want to keep your phone but get a 4G data SIM. EE's network is bigger and faster than any other in UK, and has even won awards for its reliability. By getting this 4G data SIM with EE, you'll benefit from faster internet speeds - perfect for streaming music, watching videos, playing games and uploading photos to Facebook and Twitter.
There's nothing better than a nice bit of 4G at a low price. And for that, we like this SIM plan from FreedomPop that gets you unlimited texts, unlimited minutes, and 16GB of data for the first 3 months and 4GB thereafter. At only £9.99 a month, we'd recommend this plan for anyone who doesn't want to splash out too much, but still wants plenty of data to check Facebook and stream a bit of music on the go.
This TalkTalk Mobile plan normally gives you 700MB data, but get it now and you'll get a massive 2.1GB data a month instead. That's pretty huge, but what makes this a really big deal is that it's half price for 12 months! Just bear in mind you have to be a TalkTalk broadband customer to get it.
O2's latest deal is fantastic for heavy users. This 12-month contract also includes unlimited minutes and texts, so you can communicate with friends and family with no restrictions. Factor in the fact that it's a 4G plan, and O2 has great coverage, and you have one heck of a bargain.
The great thing about getting a SIM deal from Virgin Mobile is that whatever data tariff you choose, anything you send and receive through WhatsApp or Facebook Messenger doesn't come out of your monthly allowance. You'll also get inclusive access to Wi-Fi hotspots all over the country, and data rollover, meaning any data in your allowance you don't use will be saved for the next month. And guess what - you don't even need to be an existing Virgin Media customer to get a Virgin Mobile plan.
We've researched the amount of monthly data, minutes and texts the average UK customer uses and searched through the networks for the cheapest way to get it. The overall best value SIM deal has to be with giffgaff. You get a decent allowance of internet data (4G), ample minutes, and unlimited texts.
If you don't want this deal but you like the sound of giffgaff, you can click here to order a free SIM card.
OK, so we picked out the best SIM-only deals for you, but thought those of you with an iPhone 6s might appreciate a bit of advice on what SIM card to get for your flashy handset. Here are the best SIM only deals to go with an iPhone 6s:
First up, the iPhone 6s requires a Nano SIM card size. Second, this beautiful piece of Apple technology is built to work amazingly well on fast internet. If you want to get the most out of what the iPhone 6s has to offer then we suggest going for a 4G plan. The phone has a large crystal clear display, perfect for enjoying online streaming services such as movies on Netflix and live sport from Sky and BT. For peace of mind, we suggest a heavy data allowance. Go for Three if you want lots of data, or go for BT Mobile if you want fast speed and FREE BT Sport via the BT Sport Lite app.
Not sure if you need a Micro, Nano or Standard SIM for your phone? You can get a comprehensive list of handsets and their respective SIM card size on our SIM Only comparison calculator. Here's a quick overview:
Got a new phone? If you've got one of the latest phones (like an iPhone 6, 6 Plus, 5C or 5S) then you will need a Nano SIM. Among many other handsets, Nano SIMs are also used in the HTC One (M9) and the Sony Xperia Z3 and Z3 Compact.
Got an iPhone 4S or a Samsung phone? For the older iPhones you will need a Micro SIM. Almost all Samsung phones take the Micro SIM card too. Micro SIM cards can come on their own, or as part of a Combi-SIM - either is fine. A Combi (or combination SIM) is simply a Micro SIM card that can be popped out of a Standard SIM card template, so that the SIM card can be used for phones that take either Standard or Micro SIM card sizes.
Got a Blackberry, an old smartphone or a non-smartphone? Most of the older Blackberry handsets use the standard SIM card size. Only the Blackberry Z and Q series use a Micro SIM and the Blackberry Passport uses a Nano. Old dumb-phones take the standard SIM card size, such as the basic Samsung and Huawei handsets.
Combi and 3-way SIMs: To make things simpler, some networks now offer Combi and 3-way SIM cards. A Combi SIM is a Standard SIM card with a Micro SIM card inside. You either use it as it comes, for a standard phone, or punch out the Micro SIM if you want to use the card for a phone that takes Micro SIM cards. A 3-way SIM does the same, but also incorporates the Nano SIM card size too, meaning you can use a 3-way SIM card for any type of phone. We got there in the end!
If you're still unsure what SIM card size you need then check on our SIM Only comparison calculator that we've linked to above.
Thinking about switching networks, but not sure on the next step? Check out our handy guide on switching your mobile network and keeping your number, and we'll guide you through the surprisingly simple process.