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The best unlimited data SIM only deals in April 2021

Unlimited data SIM only deals are an excellent option for those who find themselves powering through data on the move. And with prices looking more affordable than ever, it's a pretty tempting sell.

While it may sound slightly overkill, this is the direction the market is heading, covering you completely without you having to keep an eye on your data caps.

And now that many unlimited data SIM only deals allow for tethering of additional devices, you can connect laptops, gaming consoles, tablets and more to your unlimited data SIM to cover more than one device.

While some unlimited plans do involve a pretty large cash investment, there are a number of networks who have considerably brought the prices down including Three, Smarty and Lebara at times.

And with most networks now incorporating 5G, an investment in unlimited data is perfectly timed with this new rollout of better latency and much faster speeds.

If you already know you want an unlimited data SIM only deal then this will be easy! Simply use our comparison chart below to find the best price for you. Still undecided? Scroll down to find out more.

And if unlimited data is a bigger commitment than you're ready to make, consult our SIM only deals guide for the best options across all price points.

What is the best unlimited data SIM?

Right now, the best unlimited data SIM comes from the Three network. It costs just £16 a month while securing you unlimited data, calls and texts on a 5G SIM.

That's the cheapest price around right now and the cheapest ever for unlimited 5G data. If you'd rather operate on a 1-month rolling basis, Smarty's £20 a month option is a great alternative. 

Choosing the right unlimited data SIM:

sim

(Image credit: William_Potter)

Do I actually need unlimited data?

Realistically, most people won't actually need unlimited data. If you're the kind of person who's using 20GB of data as an absolute max then this is going to be slightly overkill.

If you're constantly exceeding your data caps or find yourself out of data every month, it could well be the perfect investment for you. Plus, with prices now so low for unlimited data, it could simply be worth the jump even if you won't use it all - consider it a safety net.

If you have dodgy internet, travel a lot or know you'll need to tether other devices for some reason, it could well be the perfect way to go.

How long will my contract be?

This completely depends on which network you opt for. Go for Smarty, Voxi, iD Mobile or Giffgaff and you'll only be tied in for 1 month at a time on a rolling contract.

Most other networks offer unlimited data SIM only deals on either a 12, 18 or 24 month contract. Realistically, the most common option is 12 months. You'll rarely see 18 month options and 24 month options will pop up occasionally to save you money.

Which network offer unlimited data and which is best?

Most of the main networks now offer unlimited data. This includes Three, EE, Vodafone, O2, Virgin, iD Mobile, Voxi and more. However, not all networks have an unlimited plan and some have catches to them.

Smarty and iD Mobile for instance both offer unlimited data plans at low prices...but neither is a 5G network yet. Vodafone has unlimited data but to get a good price, you'll have to have imposed speed restrictions. EE too has unlimited data but charges some big prices to get it.

Three arguably has the best options for unlimited data. It's one of the four main networks, it's 5G-enabled and almost always has one of the lowest prices around.

Unlimited data SIMs by networks:
EEO2VodafoneThreeiD MobileGiffgaffVirgin MobileTesco MobileVoxiSmarty
5G enabled?YesYesYesYesNoYesYesYesYesNo
Pros:UK's fastest speedsFree Disney PlusVeryMe reward schemeCheapest aroundCheap1-month rolling contractsAffordable pricesClubcard discounts1-month rolling contractVery cheap
cons:ExpensiveExpensiveSpeed restrictionsNo added benefitsNo 5GNo major incentiveNo major incentiveNo unlimited calls and textsCheaper prices availableNo added benefits

Can I get an unlimited data only SIM?

Unfortunately, unlimited data only SIMs aren't exactly common place. While you can get a SIM with a lot less data for your tablet or another internet connected device, unlimited data won't be available.

There is a pretty simple workaround though. As we mentioned above, most of these SIM plans allow for tethering. That means you can simply connect your tablet to your phone's SIM plan and voila - you're all sorted.

Of course, the other option is to find a data only SIM deal with less data. 

Switching to an unlimited data SIM:

SIM only deals

(Image credit: ra-photos)

How to switch to unlimited data SIM only deals:

While it used to be a tricky procedure, changing phone plans is actually extremely simple nowadays.

Firstly, you need to know you're eligible to switch plans. If your contract still has a few months until it ends, you are likely to be charged for the remaining time meaning it is usually best to fully finish your contract first.

Switching and keeping your number:

Once you know when your contract is finishing and you've got your new deal, you need to decide if you want to keep your number. If so, you can request a PAC code (Porting Authorisation Code) from your old network. This can be done via the phone or through a text.

Then you simply get in touch with your new provider and give them your new code. Each phone number or text code to get a PAC code is different for each network - all of them list this information clearly on their websites.

Switching with a new number:

Don't want to keep your number - it's even easier! Simply get in contact with your new provider and tell them you want a new number and tell your old network your ending your contract.

This can also be done via a text to switch service. Simply text STAC to 75075.

Is my phone locked to a network?

If you're looking to get a new SIM plan for an old phone - whether its yours or one you bought secondhand - you could find that it is locked to a network. This is where a phone has had a SIM in it and now can only use that network.

While that sounds permanent, it's actually easily fixed. First, try putting a SIM card from another provider into your phone. Make a call and if you can't then its locked. You can also get in contact with your network to find out if its still locked.

How to unlock a smartphone:
Unlocking a smartphone is either a breeze or a bit more complicated depending on the network its locked to:

  • EE Once six months have gone by on your contract, you can call EE on 0800 956 6000 and pay them £8.99 to unlock your phone. It says it will take around 10 days to complete. PAYG phones can be unlocked for free. Both iPhones and Google devices unlock for free after a certain time with EE.
  • O2 Whether you have an iPhone or Android device, pay as you go or on a contract, O2 can unlock it for free. You simply need to log into the O2 app, select unlock my phone and you're good to go.
  • Three Fear not, all phones on Three are unlocked as standard. Shove whatever SIM you like in there, it will work a treat.
  • Vodafone The red network doesn't quite get the same marks as Three, as your phone will be locked to them on arrival. But they have made unlocking handsets absolutely free within 10 days of your request.

What SIM card size do I need?

SIM cards these days fall into three sizes and these are: Standard, Micro and Nano, descending in size. . If you're ordering your SIM only you'll likely find it arrives in a credit card sized piece of plastic out of which can you pop your microchip SIM.

It is most likely that you will receive a Combi SIM, no matter which provider you choose. The Combi SIM contains all three sizes, and you push out the one that fits your phone. This is ideal as you don't need to know your size prior to this as you can hold it up to the SIM tray and see.