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Comparison of Unlimited Mobile Data SIMs from UK Operators

Tuesday, September 24th, 2019 (7:37 am) - Score 6,895
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Over the past few months all of the three major UK mobile network operators – EE (BT), Vodafone and O2 – have joined Three UK in offering 4G or 5G pay monthly mobile data (mobile broadband) plans with “unlimited” allowances. We take a quick look at what you can get (SIM-Only) for your money and some of the caveats.

Until recently if you wanted “unlimited data” (aka – “all-you-can-eat“) then Three UK, which offers such a feature on both their mobile SIM and specialised HomeFi / Home Broadband plans, was one of the only games in town. Three’s MVNO sibling Smarty also offers such a plan.

Admittedly Virgin Media (Virgin MobileEE MVNO) also offers an unlimited data plan, although this is only available to their existing fixed broadband or TV customers. Likewise giffgaff (O2 MVNO) has an “always-on” goodybag but we don’t consider this to be truly “unlimited” because of a hefty restriction (i.e. after 40GB of data used you’ll experience a reduced data speed of 384kbps from 8am to Midnight).

Similarly Lycamobile has a “forever data” plan but, much like giffgaff, this isn’t considered to be truly “unlimited” either because after consuming 9GB of data it will reduce your mobile data speed to just 128Kbps, which is unbearably slow and many modern internet services simply won’t work properly, or even at all, at that speed.

However the race to rollout and up-sell 5G technology to consumers has changed all that. The first to jump was Vodafone in July (here) and, with two major operators now doing “unlimited“, rival EE soon decided to join the party (here). Shortly after them O2 (Telefonica) announced that they too would be going unlimited (here), although at this point it’s not like they had much of an alternative.

NOTE: Unlimited data only applies in the UK and if you roam around the EU then the rules allow operators to set a usage cap. We’ve also noticed that mobile broadband speeds often seem slower on MVNO operators (may partly depending upon their deal with the primary operator).

Unlimited Mobile Data Comparison – SIM Only

The quick comparison below only focuses upon pay monthly SIM Only plans and doesn’t include dedicated mobile broadband services, which is because not all operators have an unlimited option for their mobile broadband plans. In any case there’s often nothing much to stop you putting such a SIM into a 4G or 5G router – they all support Tethering below (but any calls / texts may go to waste).

In addition, we’ve only focused upon the cheapest unlimited data plans available from each operator and as a result have had to include Vodafone three times because their unlimited options are tiered by speed (most of the others don’t cap by speed, so it’s necessary to show the impact of Voda’s approach). Likewise we have a second entry for EE since their 5G unlimited plan costs extra.

All of the plans below come with the usual assortment of unlimited calls and texts. 3G support is assumed and O2 has yet to launch their 5G service.

Operator Monthly Price Contract
Three UK (4G / 5G) £20 12 Months
Vodafone (4G / 5G) 2Mbps £23 12 Months
Smarty (4G) £25 1 Month
Vodafone (4G / 5G) 10Mbps £26 12 Months
Vodafone (4G / 5G) Max Speed £30 12 Months
O2 (4G) £33 (£35 on 12 Months) 18 Months
EE (4G) £34 12 Months
EE (5G) £44 12 Months

Obviously the above prices don’t consider some of the value-added extras that different operators may include, such as free access to WiFi hotspots (e.g. O2), extended roaming access (e.g. Vodafone), security features, discounts on other services or access to premium content etc.

Lastly we’ll touch on the issue of soft data caps and usage restrictions. Generally mobile operators don’t allow “commercial use” on unlimited data plans, which means that doing thing likes hosting web servers (already tedious anyway given the use of CGNAT) or consistently gobbling masses of data for several consecutive months could get you moved to a more expensive business plan.

In terms of penalties for exceeding a soft cap, some operators may contact you if you’re consistently gobbling well over the stated level but they often don’t seem to take any further action, although the threat is there in the T&Cs for some of the operators. See the examples below, which also mention the data caps for EU roaming.

Extract from Terms & Conditions (Unlimited Plans)


Fair use policy applies, personal and non-commercial usage only. If you regularly use 650GB of data per month or tether 12 or more devices we may consider this to be none permitted use and have the right to move you to a more suitable plan. EU roaming capped at 20GB per month, chargeable at 0.4p per MB afterwards.


No matter what Unlimited plan you choose, you’ll have unlimited data to use in the UK. Our plans come with different maximum mobile data speeds, to match how you use your data. Our Unlimited Lite plan has a maximum mobile data speeds of 2Mbps, Unlimited has a maximum speed of 10 Mbps and our Unlimited Max plans let you access our 5G network at full speed.

Roaming data on all Unlimited data plans is capped at 25GB per month in inclusive roaming & £6/day roaming destinations.”

Three UK

Certain usage, for example, for commercial purposes, isn’t allowed under our Terms for Three Services, so we’ve set a usage cap at 1,000 GB, in order to help identify non-permitted use.

In addition to these Unlimited UK allowances, if you are a Pay Monthly customer you can use up to 15,360 data units (which converts into 15GB of data as 1 data unit converts automatically on use into 1MB of data) each month when in a Go Roam in Europe destination.”


Uncapped and Unlimited data – 15GB fair use policy applies outside UK. Personal, non-commercial use only. If you regularly tether 12 or more devices, we will consider this non-personal use and have the right to move you to a more suitable plan. We will consider usage above 1000GB/month to be commercial use and have the right to move you to a business plan.”

Some readers have also queried about unlimited data on PAYG (Pay As You Go) plans, which tend to be a bit more complicated. Three UK does an unlimited data add-on (30 day expiry) on PAYG for £35 and Smarty’s 1 month plan for £25 (above) is very close to being the same thing. Most other operators do not yet have unlimited data for PAYG plans.

Leave a Comment
24 Responses
  1. Avatar Jack Hawkins

    If you are an existing Three customer you can get a 24m contract for £16 a month and they give you a router.

  2. Avatar Toby Adams

    I reckon there will be a black friday deal from three that will do it for around £15pm for 24 months. I will be signing up!

  3. Avatar Dan

    i dont understand how vodafone can say 4G/5G and cap the speed at 2Mbps! thats basically 3G speeds being labelled as something else. i am suprised ASA have not stepped in on this.

    • Much would depend upon whether the ASA had even received a complaint and it then tends to take several months before they reach a conclusion. In Vodafone’s favour is the fact that they’re clear about the speed caps on those tariffs.

    • Avatar Dave

      Speed is not the only potential advantage of 5G and Vodafone make it clear when plans are speed capped (though perhaps some resellers could be a bit more clear).

    • Avatar Mike

      Speed caps mean you can get unlimited at a lower price, 2Mbps is a bit too low as minimum imo though.

    • Avatar John

      I have no problem with that. Its a rubbish speed limit, but they have been quite clear its there. Unlike the others making a big deal about it being “truly truly really really unlimited” and then its not.

  4. Avatar Ian

    The Vodafone Unlimited plan was really appealing to me, but the private IP means NAT restrictions for Xbox and limits on port forwarding which is a big blocker so ended up cancelling, which is a shame as it’s much cheaper compared to my fibre connection and twice as fast!

    • Avatar Mike

      You could use a VPN to open it up.

    • Avatar Fred

      Not a perfect solution but you could use Andrews & Arnold’s L2TP service to give you static IP and port forwarding over vfe. You will get a smaller MTU size – not sure if this is an issue with Xbox? Most cheap vpn services don’t support multiple port forwards.


  5. Avatar Alank

    Whilst three 4g deals at 16 pound a month May be a good deal,4g in most areas will give 2 to 5mg.Hauwei B111 router will need to be switched to 3g to give 5 to 10mg,this is because 4g is overloaded.To get more out of the all you can use SIM it may need to change to Huawei B525 router which will give you 4g and 5g.For those people like me who signed up for 12 months at 30 pound,then played 65 pound to get in early on all you can use SIM then tied us into another 24 month contract at 25 pound a month.So use your first 14 days of contract to check you have the right deal and the right router.

    • Avatar Leeman

      It depends on your area.
      I have the Huawei B311 and cant even get 1mbps down on three’s 4g network.
      Switched to 3g however, the router until recently was giving an average of 14 to 22 mbps down until they fiddled with the masts with this refarming business and now its in the single digits with still no improvements to the 4g speeds.
      Some on the B311 average 44mbps down so it really depends.
      Their 4g is overloaded and that is the consequence of giving all your customers an unlimited option at cheap prices.
      EE and Vodafone will go the same way if they do not develop and migrate customers to their 5g quickly enough.

    • Avatar Jack Hawkins

      Three now supply the Huawei 535 which gave me a significant increase in speed to 30Mbps. Before that I was using the 525 which gave 15Mbps

  6. Avatar PN

    Mark Jackson & Plusnet: Why aren’t PN Mobile haven’t got unlimited data yet as PN run by EE network?

    • Avatar CR

      Plusnet are an MVNO using EE’s network, they run their own marketing and tariffs and are not bound by what EE themselves offer, as with all the other MVNOs – Sky mobile, BT mobile, Tesco mobile etc.

  7. Avatar john

    So all except Vodafone are unlimited in name only. o2 = 650 Gb limit. Three and EE = 1000 Gb limit.

    Should we both reporting these to ASA? Would anything actually happen?

  8. Avatar apolloa

    Smarty a currently offering it’s totally unlimited plan for £18.75 a month permanently. It’s a limited time offer though.

  9. Avatar peter

    smarty’s plan is exact same as 3s for £18.75 a month with no contract , you can suspend service from the app anytime and reinstate it , only problem with smarty is you can’t call them , online contact only and can take them over a day to get back to you , but is a good option for people who do not want contracts/tie ins plus there is no credit check as the service is paid a month in advance from a nominated card / paypal / bank account

  10. Avatar dragon

    @Fred, I don’t see why the Xbox would have any issues with the lower MTU on A&A’s L2TP service, it doesn’t with most DSL services and they also run at a reduced MTU due to the PPP overheads.

    I haven’t tried actual online gaming on the xbox for a long time but certainly the updates.etc have no trouble downloading over the L2TP service. (L2TP from a virgin media connection).

  11. Avatar dee.jay

    EE for 1TB is an interesting one. I have 2 VDSL circuits that run at ~68Mb each – EE also runs about that where I live too. Maybe I could get to 200mbps running 2 x VDSL and a cell phone? 😀

  12. Avatar Richard

    Be caareful with MVNOs. I had a 4G signal on TescoMobile – 0.2Mbps. (yes 200kbps) I put a Vodafone sim in the second slot in the phone and tested back-to-back and got 30Mbps on Voda.

    • Avatar Remo

      Tesco mobile’s parent network is o2 which is a completely different network to vodafone. Most likely just better capacity for vodafone in your area

  13. Avatar Jake

    I had PAYG on 3 with Unlimited add on and they kept deleting my unlimited data way before I reached anything like the quoted 1000Gb limit.

    Three customer services are a truly appalling bunch and they treated me really badly.

    I used to despise Vodafone but have shocked the market lately with their UNLIMITED .

    I am so tempted to take up Vodafone’s unlimited 4G/5G as they simply make the others look particularly dishonest when it comes to comparing Fair Use Policies.

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