Your phone on a ski trip: the cold, the border on the piste and calling for help

Cold empties the battery, but only for a while

Apple says iPhones and iPads are designed for ambient temperatures between 0 and 35 °C. Below that, it warns, battery life can shorten and the phone can switch itself off, and charging can slow down or pause until the phone warms up. The good news, in Apple's words, is that battery life returns to normal once the device is back at a higher temperature: the cold does not damage it the way heat can.

On the mountain that means the phone that showed plenty of charge at breakfast can shut down on a chairlift. Carry it in an inside pocket close to your body rather than in the outer shell of a jacket, keep the power bank warm too, and turn on low power mode before you go up, not when the battery is already low. If the phone does die in the cold, warm it up before trying to charge it.

Ski areas where the border runs through the pistes

Several large ski areas are shared between two countries, with one lift pass for both sides. The Portes du Soleil links twelve resorts across France and Switzerland, from Avoriaz and Châtel on the French side to Champéry and Morgins on the Swiss side. Zermatt and Breuil-Cervinia share the slopes beneath the Matterhorn, between Switzerland and Italy.

Phones do not follow lift maps. Near the frontier, yours connects to whichever mast is strongest, and that can be a Swiss network while you are still skiing in France. For a plan from the EU this matters: Switzerland is outside EU roaming rules, so your operator charges whatever its own tariff says there. The welcome text message that arrives when you change country is the giveaway. If it lists prices, check the network name in your phone settings before you keep using data. Our guide on manual network selection shows how to stay on one network.

Switzerland and Andorra cost more than the rest of the Alps

Skiing in France, Austria or Italy on an EU plan is simple: EU roaming rules give you your home allowance there. The two exceptions skiers run into are Switzerland and Andorra, neither of which is covered by those rules. Our guides on roaming in Switzerland and on Andorra and the other microstates explain what operators usually do there.

If you would rather not depend on your tariff, a travel data eSIM avoids the question. Snoozim's Europe pack covers 33 countries, Switzerland, France, Italy and Austria included, so a day that starts in Morzine and ends in Champéry uses the same plan on both sides. Andorra is not part of it and has its own pack. Your usual line stays on the phone for calls and texts.

What you actually use data for on the mountain

A ski day is light on data compared with a city break. The useful things are small: the resort's lift and piste status, the weather and webcams, messages to find your group at lunch, and a photo or two. What eats into the day is not the data but the battery, because a phone searching for signal in a high valley works hard.

So download the heavy things at the hotel on Wi-Fi: the piste map, usually offered as a PDF or inside the resort's app, and the offline area for the village in Google Maps, which our offline maps guide explains. Live location sharing with your group, through Google Maps or Find My, is handy for meeting up, but it keeps the phone's location running all day, so switch it on when you need it and off afterwards.

Calling for help in the Alps

112 is the emergency number across the EU, and it also works in Switzerland. The Swiss federal portal ch.ch describes it as the most important emergency number there and says it works with foreign SIM cards and with prepaid cards that have no credit left. It connects you to the police control centre, which passes the call on.

Switzerland also has its own air rescue service, Rega, on 1414, and a free Rega app that sends your position to its operations centre and opens a call. Rega says the app is in the app stores of Switzerland, Liechtenstein, Germany, Austria, Italy and France, that it needs location sharing switched on and at least minimal network coverage, and that abroad it needs mobile data to send your live position. If you are not sure which side of the border you are on, Rega recommends trying its app first. If you know you are outside Switzerland, call 112.

The night before the first lift

• Charge the phone and the power bank, and pack a short cable that fits in a ski jacket.
• Download the piste map and the offline map of the resort while on the hotel Wi-Fi.
• Check whether your ski area crosses a border and, if it does, what your plan charges on the other side.
• Save 112 and, in Switzerland, 1414 in your contacts, and install the Rega app if you ski there.
• Agree a meeting point with your group, so a flat battery does not mean a lost afternoon.

If you are travelling on a data eSIM, set it up at home and check the compatibility page first: a mountain hut is a poor place to discover your phone is locked to its carrier.