How to use your phone while travelling abroad

Your phone is now the map, the ticket, the translator, the boarding pass and the way you pay for the bus. It is also the single easiest way to come home to a bill larger than the flight.

There are three ways to get connected abroad, and the right answer depends almost entirely on how long you are going and where.

Option 1: eSIM

An eSIM is a SIM card downloaded as software rather than posted as plastic. You buy a data plan online, scan a QR code, and your phone runs it alongside your normal number.

Good at: being ready before you land. No queue, no shop, no swapping a tiny piece of plastic over a hotel sink and losing it. You keep your home number active for calls and, crucially, for SMS verification codes from your bank.

Weak at: price per gigabyte on long stays, and phone calls - most travel eSIMs are data-only, so you make calls over the internet instead. Coverage is also whatever local network the provider has partnered with, which is not always the best one.

Requires: an eSIM-capable and carrier-unlocked handset. Most phones released in the last five or six years qualify, but check yours specifically before relying on it.

Best for: trips of a few days to a few weeks, multi-country trips, and anyone who values arriving connected.

Option 2: a local SIM bought on arrival

Good at: price and coverage. A local prepaid SIM is almost always the cheapest data available and gives you a local number, which matters for taxis, deliveries, restaurant bookings and anything that sends a confirmation code.

Weak at: the first hour. You need to find a shop, sometimes register with a passport, and in some countries wait for activation. Airport kiosks charge a premium; a phone shop in town is usually half the price.

Best for: stays of a month or more, and any country where you need a local number to function.

Option 3: roaming on your home plan

Good at: doing nothing. Your number, your plan, no setup.

Weak at: cost, outside the regions where roaming is regulated. Within the European Economic Area, "roam like at home" rules mean EU and EEA residents generally use their domestic allowance at no extra charge. Outside such arrangements, per-megabyte roaming rates are the most expensive data you will ever buy.

Many operators sell a daily travel pass - a fixed charge per day of use that unlocks your normal allowance. These are convenient and mid-priced; over a two-week trip they usually cost several times an eSIM.

Best for: short trips inside your regulated roaming region, and anyone who needs their own number to ring.

How not to get a shocking bill

Almost every horror story comes from the same three causes: an app updating in the background, a video autoplaying, or a phone silently roaming on a network you did not choose.

Before you fly:

• Turn off data roaming in your phone's settings, and only turn it back on deliberately once you know which network and plan you are on.
• Set a data limit and a warning in your phone's mobile-data settings.
• Turn off automatic app updates over mobile data, and automatic photo and cloud backup.
• Ask your operator to place a spend cap on the account. Many will do it free and it converts a catastrophe into an inconvenience.
• Disable Wi-Fi Assist / Adaptive Wi-Fi, which silently switches to mobile data when wifi is weak - a common cause of unexplained usage.
• Beware ferries and cruise ships. Maritime and in-flight networks are not covered by roaming deals and are charged at extraordinary rates. Use flight mode at sea.

Download everything before you go

The most useful travel tech habit costs nothing and works with no signal at all.

• Offline maps for every city and region you will visit. Both major map apps do this, and offline search and walking directions work fully.
• Offline translation packs for the local language, including the camera mode that reads menus and signs.
• Boarding passes, hotel confirmations, insurance documents and your passport photo page, saved as files rather than links - a link is useless without data.
• Music, podcasts and something to read, for the twelve-hour bus.
• Your itinerary as a plain document with addresses in the local alphabet.

Wifi, and being sensible about it

Public wifi in cafés, airports and hotels is convenient and not private. The practical rules:

• Do not do banking or enter card details on an open network unless you are using a VPN.
• Prefer your mobile data for anything sensitive - it is encrypted by default.
• Turn off automatic connection to open networks, which stops your phone joining anything that shares a name with a network you once used.
• A reputable VPN is worth having, both for security on hotel networks and for reaching services that geo-block from abroad.

Calls, and the SMS problem nobody plans for

Data-only eSIMs mean calls happen over the internet, which is fine for most people. The failure mode is different: SMS verification codes. Banks, airlines and government services still send one-time codes to your home number, and if your home SIM is out of the phone or roaming is off, you will not receive them.

This strands travellers regularly. Two fixes: keep the home SIM installed and active for SMS while using an eSIM for data, or move your accounts to an authenticator app before you travel.

The physical side

• A power bank of at least 10,000 mAh. Note that airlines require lithium batteries in cabin baggage, never in the hold, and there are capacity limits.
• A multi-port charger and one universal adapter, so a single socket charges everything.
• A short cable for the plane and the bus.
• Cold and heat kill batteries. At minus twenty a phone can shut down at 40%; keep it in an inside pocket.
• A cheap case and a screen protector cost less than any repair abroad.

A five-minute pre-flight routine

1. Turn off data roaming.
2. Install and activate your eSIM, or confirm your roaming plan.
3. Download offline maps and a translation pack.
4. Save tickets, bookings and insurance as offline files.
5. Check that your bank can reach you - authenticator app, or home SIM staying in.
6. Charge the power bank and pack it in your cabin bag.

Six steps, and the phone stops being a liability and goes back to being the most useful object you are carrying.