The short answer
A power cut can interrupt charging, Wi-Fi, mobile networks, transport, card payments and power-dependent medical equipment at the same time. Confirm the affected place and instructions with the accommodation, utility or local authority; protect immediate health, light, temperature and evacuation needs before using the phone. A travel eSIM neither supplies electricity nor guarantees a working mast. It may support limited ordinary online tasks only while a compatible unlocked phone has power and reaches a supported network.
Verify the affected place, cause and official instruction
Establish whether the loss affects one room, the whole property, a street, a transport hub or a wider district. Ask the accommodation or site manager to check its electrical safety and official utility notice; use the responsible local authority for any shelter, closure or evacuation instruction. Record the time, exact address, reported extent and next update. Do not touch damaged wiring, enter a restricted area or assume a social post explains your location. A weather warning and a power outage are different events: follow both authorities when both exist.
Put medical power, fire and temperature risks first
Use the locally applicable emergency channel for immediate danger. Tell staff or responders promptly about oxygen, mobility equipment, refrigerated medicine or any other power-dependent medical need; obtain device-specific advice from the responsible clinician or supplier rather than guessing battery or storage time. Use generators, flames, heaters and cooking equipment only under competent local instructions: carbon monoxide, fire and electric shock are not connectivity problems. Move to an officially identified powered or safer location when instructed, and never delay help to install an eSIM or search for a charger.
Turn the remaining battery into an offline continuity pack
Lower brightness, stop background updates and cloud backup, and reserve power for official updates and necessary contact. Save the accommodation address, outage reference, transport booking, meeting place and one trusted contact so they open offline. Download only the map area still needed and test it without a connection; offline maps can omit walking, cycling and public-transport directions, live traffic and alternative routes. Keep a torch separate from the phone where possible. A power bank has a finite charge, and a public socket or charging station is not safe, available or authorised merely because it appears on a map.
Revalidate accommodation, transport, payment and access
Ask each responsible provider what still operates: lifts, room access, water, heating or cooling, reception, rail, metro, airport transfers, fuel, cash machines and card terminals may fail independently. Obtain a confirmed replacement or instruction before travelling across a dark or closed area. Preserve concise notices and reasonable receipts without publishing booking references or identity details. If the stay, departure date, station or country changes, rewrite the itinerary and confirm each leg. Electricity restoration at one building does not prove that transport, merchant systems, Wi-Fi or mobile infrastructure along the route has recovered.
Keep alerts and urgent contact independent of mobile data
Write down the official alert method, staffed help point, local emergency number and a precise offline meeting plan. Current CheapESIM offers list data but no carrier calls or SMS, so they do not provide a conventional emergency call, government cell broadcast or local telephone number. Internet messaging may fail through an empty battery, mast backup exhaustion, congestion, account access or the same outage affecting the recipient. Do not make one app, live location or one phone the only route for a child, dependent traveller or separated companion. Agree who acts, where and when without waiting for a message.
Compare data only for the powered, non-critical remainder
After safety, medical power, official instructions, offline essentials and independent contact are secured, list only ordinary remaining tasks such as checking a confirmed provider update or sending a non-urgent accommodation message. Subtract working home roaming, trusted restored Wi-Fi and offline material. Continue only if the phone can be charged safely, every required country is listed, validity and activation cover the revised stay, allowance is measured and the exact unlocked device is compatible. Stop if you need electricity, guaranteed reception, alerts, calls, SMS, hotspot, emergency access or proof that local services work.