How do I find the best deal for me?

Several factors will come into play when choosing the right SIM only deal for you.

You should consider the length of your deal, how much you want to spend, your monthly data allowance and whether you’re interested in additional perks or prefer a no-frills bundle.

1. Have a budget in mind

You can currently get a SIM only deal for as little as £1.58, if you're happy with 1GB per month of mobile data. It’s not a huge amount but it may be enough if you don't use your mobile very often while out and about.

The more data that's included in the deal, the more you'll often have to pay. You also shouldn't have to pay more for a 5G deal, as most major networks now include 5G as standard at no extra cost.

While SIM only deals can change, they indicate how much you can save compared to a pay-monthly mobile phone contract.

2. Choose the right amount of data

According to Ofcom's 2024 Communications Market Report, the average mobile phone owner used about 9.9GB per month while connected to mobile data on their smartphone. That covers browsing the web, watching videos, using social media and anything else you do on your phone when on the go.

So you may think you need unlimited data, but in reality, a much smaller package would be more than enough. The less data you need, the more money you can save, as smaller bundles are usually cheaper than big data plans.

If you want to see how much data you're using, all you have to do is take a look at your network's app on your phone. There, you should find a detailed breakdown of exactly how much data you use on a monthly basis.

3. Pick your preferred contract length

The length of contract you choose comes down to your personal preference. You can usually choose from:

• 30-day deals: These short-term plans are perfect for people who want a no-commitment SIM deal. You can keep the plan rolling for as long as you like, but you can also cancel and switch to a new plan at any point after the initial 30 days. You’re more likely to get a cheap 30-day deal on a smaller network like Lebara, giffgaff or SMARTY.
• 12-month deals: Opt for this type of deal, and you’ll be committed to using it for a year. After that, you can keep using it or switch over to a new plan at any time.
• 18/24-month deals: These are ideal if you want to sign up for a SIM only deal you’re happy with and not worry about finding a new one anytime soon. Longer deals are common with larger networks like Vodafone and O2.

How easy is it to switch networks?

If you want to switch networks to find a better deal, you first need to work out how long your existing contract is remaining. To find this out, you can log into your network's app or website, contact their customer service team, or text INFO to 85075.

However, if you’re still in the middle of your contract, you’ll have to wait for the plan to end before you switch over to SIM only unless you’re willing to pay an early cancellation fee.

When you're approaching the end of your contract, your network is now obliged to send you an end-of-contract notification.

Thanks to the introduction of text-to-switch legislation, switching networks is as simple as sending a text once you're out of contract.

Will I lose service if I switch to another network?

Moving networks is usually a near-seamless process, and you're not expected to be out of service for a noticeable period of time. After you've given your new network your PAC code, you'll still be able to take calls and receive texts.

When you switch to your new network, you may lose service for a short while, often only a matter of minutes.

When the transfer is done, just put your new SIM into your phone and switch it on. If the phone works and you can make calls, you've got service, and you're all set.

When will my new SIM only contract start?

Your new SIM only contract will usually start when your SIM card has been dispatched. If it’s a physical SIM card, just insert it into your smartphone, and you’ll be good to go.

If it’s an eSIM, you’ll need to follow your network’s set-up instructions, but activating the eSIM in your phone’s settings is usually straightforward.

Will I need to unlock my phone to use it with a new SIM only deal?

Since December 2021, networks haven't been allowed to sell locked phones, so if you got your phone after this date, it should already be unlocked.

A locked phone can only be used on the network you bought it on, but this can differ depending on which network, handset and plan you have. However, there's a simple way to see if your phone is unlocked.

If you’re on an iPhone, go to: Settings > General > About and scroll down until you see Network Provider Lock. Your phone will be unlocked if it says, ‘No SIM restrictions’. But if there’s a network’s name there, it is locked.

If you use an Android device, the method is very similar. Go to Settings > Connections > Network and Internet > Mobile network > Choose network. If you can now see several networks, your phone is unlocked. But if only one is showing, your phone is locked to that provider.

Check out our guide to unlocking your mobile phone for more details.

Once you’ve confirmed that your phone is unlocked, you're now free to get a new SIM. The next thing to do is find a SIM only deal that suits your needs.

Which network should I join?

We offer deals from most major UK mobile networks. You can compare SIM only contracts from Vodafone, O2, SMARTY, VOXI, Three, giffgaff and more.

Although the likes of giffgaff and VOXI may not be as instantly recognisable as high-street names like Three and O2, they're certainly brands you can trust. That's because their service is based on the larger providers' networks, which they pay a fee to use.

For instance, VOXI operates through Vodafone. So despite having a different name, different plans, and different prices, VOXI’s coverage, speed, and quality will be the same as those of Vodafone.

In fact, many smaller networks offer market-leading call rates and data deals, so they can often work out cheaper than more well-known networks.

However, larger networks tend to offer more benefits and customer support.

To keep prices low, some smaller networks don't operate a call centre and offer online support only. With a big-name network, you’ll usually always be able to speak to a person if you need help with your account.

And don’t think benefits like O2 Priority Tickets and Vodafone’s VeryMe app are reserved for the major providers. Smaller networks offer incentives too, like VOXI’s data-free social media, iD's data rollover and Tesco Mobile’s Clubcard points.

For more information on each network’s perks and features, check out our dedicated network pages for Lebara Mobile, Tesco Mobile, Virgin Mobile O2, Sky Mobile, iD Mobile, Asda Mobile and Lyca Mobile.