If you are travelling in Europe and plan to make calls, send texts or use data, a local SIM card can cut your bill dramatically. But registration rules, activation steps and top-up methods vary by country. This guide explains what to expect so you can get connected quickly.

Why a local SIM is usually worth the effort

Since the UK left the EU, most UK mobile operators have reintroduced roaming charges for Europe. Even where roaming is included, fair-use limits apply and data speeds may be capped. A local SIM gives you a local number, so calls within that country are cheap and data is often far more generous. For stays of more than a few days, the savings easily cover the SIM and a top-up.

A local number also makes life easier for restaurant bookings, delivery drivers or local contacts. It stops you burning through your UK allowance, which can be expensive if you exceed it.

Registration rules: what you need to know

Many European countries require you to register a prepaid SIM with identification. This is an anti-fraud measure and is strictly enforced. In Germany, Italy, Spain, France and Belgium, you must show a passport or national ID card. Some shops may ask for a local address or tax number, though this is not always the case for tourists. In Italy, a codice fiscale (tax code) may be requested for certain plans, but a passport usually suffices for a basic prepaid SIM. In Spain, a passport or NIE is accepted. In France, a passport or ID card is standard.

A few countries, such as the Netherlands, do not require registration. Always carry your passport when buying a SIM, as digital copies are rarely accepted.

Where to buy a local SIM

Airport kiosks are convenient but often charge a premium and sell poor-value tourist plans. Official carrier shops in city centres are best for advice and activation, though you may queue. Large supermarkets, convenience stores and petrol stations sell starter packs, but staff may not help with activation. In France, tabac shops are common; in Italy, look for kiosks or phone shops. Avoid unofficial street sellers, as the SIM may not be registered properly or may stop working.

If you have an eSIM-compatible phone, you can buy a data plan online before you travel. This is often easiest, though you may not get a local phone number. For international calling, a physical SIM with a voice plan is more flexible.

Activation steps: from unboxing to first call

Activation is usually straightforward, but a few steps trip people up. Insert the SIM and power on. You may need a PIN, printed on the card holder. Some networks require you to call a number or send an SMS to activate; others activate automatically.

• Top up: buy a voucher, use the operator's app, or dial a USSD code. Keep the receipt.
• Check APN settings: most phones configure these automatically, but if data fails, enter the access point name manually.
• Enable data roaming: if your local SIM uses a partner network, turn on data roaming in your phone settings.
• Test: make a call, send a text and load a web page. If something fails, restart and check settings.

Keeping your UK number and using dual SIM

Most modern phones support dual SIM, either two physical cards or one physical plus an eSIM. This lets you keep your UK number active for incoming calls and texts – useful for banking codes – while using the local SIM for data and outgoing calls. Be careful: receiving calls on your UK SIM abroad can incur roaming charges, so consider forwarding to voicemail or using a VoIP service. You can set the local SIM for data and the UK SIM for calls, but check your operator's rates.

For international calling, a local SIM often offers cheap add-ons for calls to the UK. Alternatively, use a VoIP app over local data. This is usually cheapest, but call quality depends on your connection.

Practical pitfalls and money-saving tips

Prepaid SIMs have expiry dates. If you do not top up within 30 to 90 days, the SIM may be deactivated. Keep an eye on your balance and top up before you leave if you plan to return. Data caps can also catch you out: some plans throttle speeds after a certain amount, so read the small print.

One of the best tricks is to buy a SIM in one EU country and use it across the EU under roam-like-at-home rules. A Spanish SIM, for example, will work in France and Germany at no extra cost, subject to fair-use limits. This means you do not need a new SIM for every country. However, if you spend more time abroad than at home, the operator may apply a surcharge. Note that the UK is no longer part of these rules, so check the terms.

Finally, check network coverage before you buy. A cheap SIM is useless if the signal is poor where you are staying. Ask locally or check the operator's coverage map. With a little planning, a local SIM can keep you connected for a fraction of the cost of roaming.