Best SIM-Only Deals in the UK — A Complete Guide to Choosing the Right Plan

A SIM-only deal is a mobile plan that gives you an allowance of data, minutes and texts on a SIM card — with no handset included. You supply the phone; the provider supplies the connection. Because there is no phone to subsidise, the monthly price is a fraction of a handset contract.

SIM-only plans come in three shapes: prepaid (pay as you go, topped up with credit), 30-day rolling (a fixed monthly bundle that renews until you cancel), and fixed-term (a 12 or 24 month airtime contract). We unpack the differences in the section below.

Every SIM-only plan on GetSIMSmart runs on one of the UK's four physical networks — EE, O2, Three or Vodafone — through smaller brands (MVNOs) that rent capacity on them. You get the same masts and signal as the host network, usually for a lower price.

The core difference is what you are paying for. A handset contract bundles a new phone into the monthly price and commits you to 12–24 months of payments — that is a credit agreement, so the network runs a hard credit search to approve you. A SIM-only plan is just the airtime, with no phone, so it costs far less and (for rolling and prepaid plans) involves no credit agreement.

If you already own a phone you are happy with, SIM-only is almost always the cheaper route. If you genuinely need to spread the cost of a new handset, a contract can make sense — but over two years you typically pay more than buying the phone outright and pairing it with a rolling SIM.

Most people over-buy data by a wide margin. Before you pick a plan, open your phone's settings and look at the data figure for last month — that is the only honest number that matters. Then match it to the guide below.

Every mobile signal in the UK comes from one of four physical networks: EE, O2, Three and Vodafone. Every other brand is an MVNO that rents capacity on one of them, so coverage and signal match the host network. The brand on the SIM matters far less than the network underneath it.

Before you commit, check the host network's official coverage map for your home and work postcodes — that tells you the real signal you will get. Then weigh up price, data allowance, 5G inclusion, roaming and any spend-cap features.

Yes — for the right plan type. A network only runs a credit search when it is lending you something, usually a handset or a 12–24 month airtime contract you pay for after using it. Because a prepaid or 30-day rolling SIM is paid in advance, there is nothing to lend and nothing to underwrite, so no hard credit search is run. These plans are not credit agreements.

It is worth knowing the difference between a hard and a soft search. A hard search is visible to other lenders and can nudge your score down briefly. A soft search is invisible outside the company that ran it. Prepaid and rolling SIM-only plans do not involve a hard credit search, though a provider may still carry out identity, address or fraud-prevention checks — these are not credit searches and will not appear on your credit file.

Fixed-term SIM-only contracts of 12 months or more usually do require a hard credit check, because you are committing to pay for the full term.

A physical SIM is the familiar removable card you swap between phones. An eSIM is a digital plan downloaded straight to a compatible handset — no card to wait for in the post, and you can hold more than one plan on a single phone for easy switching or a dual-number setup.

The trade-off is compatibility: eSIM only works on newer handsets, while a physical SIM works in any unlocked phone. Several plans on GetSIMSmart offer eSIM alongside a physical card, including iD Mobile, Lyca Mobile and 1pMobile.

You do not have to get a new number when you switch. UK rules make number porting a legal entitlement, and your old provider cannot refuse it.

Text PAC to 65075 from your current phone. Within minutes you will get a Porting Authorisation Code, valid for 30 days. Order your new SIM and wait for it to arrive. Once it is in your phone, hand the PAC to your new provider — usually through their website or by text. The number transfers across, normally within one working day, and your old plan closes automatically.

If you would rather start fresh, text STAC to 75075 for a Service Termination Authorisation Code that closes the old plan without moving the number.