Choose a SIM-only plan by testing the underlying network and checking the exact features and contract terms; headline data and promotional price come later.
Use this order
- Test coverage and calling in the places that matter.
- Check the phone’s exact compatibility with VoLTE, Wi‑Fi Calling, 5G and eSIM.
- Measure real data use over representative months.
- Decide between PAYG, rolling monthly and a fixed term.
- Check roaming, tethering and fair-use rules.
- Read the contract summary and price-change wording.
- Plan number porting and account recovery.
Build a requirements list
| Requirement | Question to answer |
|---|---|
| Calls | Does VoLTE work on this exact phone and tariff? |
| Indoor reliability | Is Wi‑Fi Calling supported and provisioned? |
| Data | How much is needed, including hotspot use? |
| Travel | What countries, charges and roaming caps apply? |
| Flexibility | What is the minimum term and exit process? |
| Number | Will a PAC be used, and when? |
Do not buy by host network alone
An MVNO may use EE, O2, Vodafone or Three radio coverage but offer a different feature set. Confirm support on the retail provider’s own pages. Likewise, a phone bought abroad may not receive the same operator profile as a UK model.
Read new-contract price rises correctly
New contracts since 17 January 2025 cannot use inflation-linked or percentage-based rises for the core subscription price. If a provider includes a scheduled rise, it must be shown upfront in pounds and pence. Compare the whole minimum term rather than only the first promotional month.
Port only after the plan proves suitable
Where possible, test the new SIM with its temporary number before submitting the PAC. Keep the old service active, save recovery codes and choose a port date away from travel or critical logins.
A safe completion check
Shortlist by coverage and required features before comparing price. Confirm VoLTE, Wi‑Fi Calling, eSIM, roaming and tethering on the exact phone and tariff. Then compare allowance, term, price changes and the route to leave or port the number.
- Test the network at home and work.
- Save the advertised terms.
- Avoid a long commitment until compatibility is proved.
Official sources
Facts checked: 25 July 2026. Rules, plan features and menu paths can change. Recheck the current terms for your exact provider, plan and device before acting.
