What is a SIM only deal?

15th March 2021

Sim only deals

SIM Only deals are everywhere, most networks offer them and they’re the main alternative to a Pay Monthly contract.

But what exactly are they? And is a SIM Only deal the right choice for you? We answer all that below as well as looking at the various networks that offer them.

What is a SIM Only deal?

A SIM Only deal is a contract with a mobile network which gives you a monthly allowance of minutes, texts and data, but which doesn’t come with a new phone, so you need to supply your own handset – either by using your current one or buying one outright.

How does SIM Only differ from Pay Monthly or Pay As You Go?

Whereas a SIM Only deal doesn’t include a new handset, a Pay Monthly deal does, so if you need a new phone and don’t want to pay upfront for one then a Pay Monthly deal could be a better choice – but it will also be more expensive, as you’re covering the cost of a new phone as well as your allowances.

Pay As You Go simply means paying for the allowances that you use. There’s no contract (though some networks do offer monthly bundles similar to a 30-day SIM Only deal). For ultimate flexibility Pay As You Go is the way to go, but you often get better value on SIM Only, as you’re typically tied into a contract.

What are the advantages of a SIM Only deal?

There are two main advantages to a SIM Only deal. The first is price. As you’re not paying for a handset as part of it, the costs of SIM Only are usually a lot lower than Pay Monthly for the same allowances, and as you’re often tied in to a contract for up to 12 months it will even often be cheaper than Pay As You Go, to make that commitment worthwhile.

The savings are sometimes so great that even if you want a new phone it can often work out cheaper to simply buy the handset and then get a SIM Only deal than to get the phone on a Pay Monthly contract.

The other advantage is flexibility. While Pay As You Go is more flexible still, you’re rarely committed for more than 12 months on a SIM Only deal, which is half the length of a typical Pay Monthly contract. And many SIM Only offers last just 30 days, giving you even more flexibility.

Are there any disadvantages to a SIM Only deal?

As noted above, you don’t get a new handset with a SIM Only deal, so if you want one and don’t fancy paying for it outright then a SIM Only deal might not be the best option.

Otherwise, there’s generally very little downside to a SIM Only deal assuming you can find one with the allowances you want (as these also sometimes differ from Pay Monthly). 

Which networks offer SIM Only deals?

Most networks offer SIM Only deals, you’ll find a brief overview of all the ones we sell below.

Note that the information below was accurate at the time of writing, but the deals you see on this site will always be up to date.


EE offers 12-month and 24-month SIM Only plans with data limits that top out at unlimited.

The network also boasts comprehensive 4G coverage, with over 99% of the UK population covered, and very high speeds. It also offers 5G on many plans.

EE additionally offers ‘Smart Plans’ that come with between one and three additional benefits.

These include things like the ability to roam for free in the US, Canada, Mexico, Australia and New Zealand, an Amazon Prime Video subscription, a BT Sport subscription, an Apple Music subscription, a BritBox subscription, and the option to use select streaming services without it coming out of your data allowance.

The network also lets you tether, with no limits other than your data allowance, roam for free in the EU, and – with supported handsets – make 4G and Wi-Fi calls.


Three stands out primarily through often low prices relative to the other major networks and unlimited data allowances on certain plans. 5G also comes as standard on all of its plans and you can roam for free in numerous locations beyond Europe. Plus, the network has 99.8% 4G population coverage.

Three offers SIM Only deals in 1, 12 and 24-month flavours and lets you tether with no real restrictions other than your data allowance.

Three also supports Wi-Fi Calling and 4G Calling with select handsets.


O2 currently has over 99% UK population coverage with 4G, and a growing 5G network, so it’s in the same ballpark as rivals. O2 also offers 30-day, 12-month and 18-month SIM Only plans, with up to unlimited data.

One of the main advantages of O2 is its Priority service, which gives customers early access to event tickets, as well as free things, discounts and competitions.

You can tether on O2 and roam for free across most of Europe – and even further on some plans, as well as making use of both Wi-Fi Calling and 4G Calling (with a supported handset).


Vodafone has over 99% 4G population coverage in the UK and that figure is growing all the time. It also has growing 5G coverage and offers 5G SIM Only plans.

But perhaps the biggest selling point of Vodafone SIM Only is that on the top-end packages you get an included subscription to Amazon Prime Video, Spotify Premium, or YouTube Premium.

Vodafone also lets you roam for free in Europe (and even further afield on some plans), use your data for tethering, and has SIM Only plans that offer up to unlimited monthly data, and come in 30-day, 12-month and 24-month durations. The network also supports Wi-Fi Calling and 4G Calling.


BT Mobile uses EE’s infrastructure, meaning it’s got over 99% UK population coverage with 4G. It also offers 5G in the same places as EE, and this comes as standard on SIM Only plans.

Plus, BT gives its customers free access to its five million Wi-Fi hotspots, and many plans also give you access to BT Sport on your phone.

You can also tether, and – with supported handsets – make Wi-Fi and 4G calls. If you’re a BT broadband customer then you can also get discounted prices.

BT’s SIM plans also include European roaming and they come with up to 100GB of data (or unlimited if you’re a Halo customer). However, they’re all at least 12 months long, so not as short term as some networks offer.

Tesco Mobile

Tesco Mobile uses O2’s infrastructure, but it stands out largely through its low prices.

Tesco SIM Only plans are available with up to unlimited data and you can choose either a 12-month or 18-month plan. There are also plans that include 5G data.

Tesco Mobile additionally includes tethering and European roaming at no extra cost.

iD Mobile

iD Mobile has a range of low cost SIM Only plans, offering up to unlimited data, and many of its plans are just 30 days long, so you’re not tied in – though there are also 12-month options.

iD Mobile also stands out through offering Data Rollover, which lets you roll over unused data from one month to the next one, so it doesn’t go to waste – though obviously this doesn’t apply on unlimited data plans.

The network also allows for free roaming across much of Europe and allows tethering on its plans. You can even use 4G Calling and Wi-Fi Calling with select handsets, which is rare on MVNOs (mobile virtual network operators).

Sky Mobile

Sky Mobile SIM Only plans come with up to 60GB of data and all last 12 months. The network also offers data rollover and lets you switch your allowances every month. Plus, Sky TV customers can use Sky apps without the use coming out of their data allowance.

Sky Mobile also allows tethering, EU roaming, Wi-Fi Calling and 4G Calling.


VOXI SIM Only plans use Vodafone’s network, and top out at unlimited data. All SIM Only plans are just 30 days long, and many include 5G.

VOXI also allows you to use Snapchat, Instagram, WhatsApp, Facebook, Twitter, Pinterest, and Facebook Messenger without it coming out of your data allowance, and on some plans you can additionally use Netflix, Amazon Prime Video, YouTube, My5, TVPlayer, and UKTV Play without it coming out of your data allowance.

VOXI also lets you roam for free in most European countries, and you can tether.

Virgin Mobile

Virgin Mobile SIM Only plans come in 12 and 24-month varieties, so none of them are particularly short term, but they include up to unlimited data and come with 5G as standard.

They also allow you to roll over unused data, access Virgin’s network of over 3.5 million Wi-Fi hotspots, and allow messaging on WhatsApp, Twitter and Facebook without it coming out of your data allowance.

Its 5G service uses Vodafone’s coverage, and you can tether, roam for free across the EU, and use Wi-Fi Calling and 4G Calling.

Smarty Mobile

Smarty Mobile SIM Only plans are all just 30-days long, so they’re flexibly short term, and they come with up to unlimited data. There aren’t many available, but some of them include money back for unused data – so you’re only paying for what you use.

Smarty also allows tethering, free EU roaming, Wi-Fi Calling, 4G Calling, and it shares Three’s coverage and infrastructure.

Lebara Mobile

Lebara Mobile SIM Only plans are all short at just 30 days, and they come with up to unlimited data. They also include minutes that can be used to call dozens of destinations abroad, making Lebara a great choice for those with friends or family overseas.

Lebara also offers free EU roaming as well as free roaming in India – which is relatively rare among UK networks.

Can I change network or contract type?

Yes. As long as you’re not currently tied into a contract you’re free to switch network or move from Pay Monthly or Pay As You Go to SIM Only.

If moving network just make sure that your phone is unlocked though – if it isn’t your current network can probably unlock it for you.

Can I keep my number?

Yes. To do so just call your current network and request your PAC code, or alternatively text the word ‘PAC’ to 65075 from the number you want to keep. Then place your SIM Only order, activate your new SIM, and give your new network your PAC code and the number you want to keep. The speed of the transfer will depend on the network you’re using, but usually it happens within a couple of days. Find out more.

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