Cheapest SIM-Only Deals

Finding the cheapest SIM-only plan

The cheapest UK SIM-only plans are almost always from MVNOs - smaller operators that lease capacity from the four big networks and pass the wholesale rate to customers. Sub-£10 plans with 5GB+ of data and unlimited calls and texts are routine on giffgaff (O2 network), Smarty (Three), 1pMobile (EE) and iD Mobile (Three), and a handful of plans dip below £5 a month for lighter users. The same MVNOs power our no credit check SIMs shortlist, so cheap and contract-free usually overlap. The cheapness comes from operational lean-ness, not lower service quality - the underlying mobile signal is identical to the host network. The trade-off tends to be customer service: online-only support rather than physical shops, and sometimes lower priority access during congestion. For most people, those are easy compromises. When sorting by price, look at the headline monthly cost plus the data allowance together - a £6 plan with 2GB might be a worse deal than a £8 plan with 30GB if you actually use mobile data. Also watch the contract term: rolling plans on MVNOs typically match the headline price month after month with no annual increase, while 12-month plans on the big four can creep up on the April price-rise schedule.