SIM Only Deals & Mobile Contract Discounts

Choosing between a SIM only deal and a full mobile contract comes down to one question: do you need a new handset, or just better-value airtime? With four host networks in the UK and dozens of providers piggybacking on them, the same allowance can cost wildly different amounts depending on who you buy from. BudgetFitter tracks verified SIM only and pay monthly offers across the major networks so you can compare data, minutes and contract length side by side rather than guessing at the checkout.

How to find the best SIM only and mobile contract deals

SIM only versus pay monthly contracts

A SIM only plan covers airtime alone, so if you already own a phone it is almost always the cheaper route. A pay monthly contract bundles a handset into the same bill, spreading the cost of the device over the term. Networks such as Three and Vodafone UK offer both, while specialists like SMARTY Mobile focus on stripped-back SIM only plans. Look for welcome offers and discounted first-month pricing, but always check the price you pay once any introductory period ends.

Data allowances and 5G

Be honest about how much data you actually use. Light users streaming over Wi-Fi at home rarely need unlimited data, while heavy mobile streamers and tetherers benefit from larger or unlimited tiers. Providers including giffgaff and VOXI Mobile publish clear allowances and, in some cases, social or app-only data perks. Check whether 5G is included at no extra cost, as it often is on newer plans.

Network coverage and host networks

Smaller providers run on one of the four host networks, so coverage mirrors the network they use rather than their own brand. Tesco Mobile and Lebara Mobile UK are examples of providers that ride established infrastructure. Before switching, check the coverage map for your home, workplace and commute, because a low price means little if the signal is patchy where you spend your day.

Switching networks and keeping your number

Switching is far simpler than it once was. Text PAC to 65075 to receive your transfer code, hand it to your new provider, and your number moves across within one working day. Rolling 30-day SIMs make switching painless, so it pays to review your plan regularly rather than rolling on out of habit.

• Work out your real monthly data use before comparing plans, not your worst-ever month.
• Prefer 30-day rolling SIMs if you value flexibility and want to keep switching for better value.
• Check the post-introductory price, not just the discounted first-month figure.
• Confirm the host network's coverage map for the places you use your phone most.
• Keep your number by requesting a free PAC code before you cancel your old plan.

Every offer surfaced here is checked against the provider's own programme, so the deal you click through to is the deal you get. Whether you want a no-frills SIM, an unlimited data plan or a contract with a new handset, comparing networks side by side is the quickest way to stop overpaying. BudgetFitter keeps the listings current so a quick look is enough to see who is genuinely worth switching to.