The monthly price of a plan is what you pay if you stay inside it. The charges that generate horror stories all come from outside it: roaming in the wrong country, calling a premium-rate number, a child with an app that texts a shortcode, or simply going over a small data allowance. The single most effective protection is one setting that most people do not know exists.
The spend cap
UK networks must let pay-monthly customers set a cap on out-of-plan charges. Set it to zero and nothing outside your allowance can be billed; set it to £10 and you have a small buffer. When you reach the cap, services that would cost extra stop working until you raise it — usually instantly, from the app. Some networks put a default cap on new accounts; many do not. Log in and check.
A few things typically sit outside the cap even when it is set: your monthly plan price itself, any device plan, and in some cases roaming charges in countries with no agreed rates. The network's help pages will list the exceptions.
The charges worth knowing about
- Out-of-allowance data. Charged per MB or in blocks. On a small plan a video call can cost more than the plan.
- Numbers starting 084, 087, 09 and 118. A service charge set by the company you are calling plus your network's access charge, per minute. Directory enquiries (118) can be several pounds for a short call.
- Roaming. Even where EU roaming is included, there is usually a fair-use data limit, and cruise ships and ferries use satellite networks that no plan covers.
- Premium texts and subscriptions. Charged to your bill via shortcodes. A spend cap stops these; you can also ask your network to bar them entirely.
For children's phones
A pay-as-you-go bundle is the simplest protection: when the credit is gone, it is gone. If a child needs a pay-monthly plan, set the spend cap to zero and bar premium services and adult content, all of which the network will do on request. Then compare pay-as-you-go bundles alongside the rolling SIM-only plans, since the cheapest option changes month to month.