A modern city trip runs on a smartphone. Transit tickets, hotel bookings, maps, ride-hail apps and restaurant reservations all assume you have data, often from the moment you land. Getting that data abroad used to mean either paying high roaming rates or hunting for a shop selling SIM cards. Today there are better options, and choosing the right one before you leave saves money and stress.
Your three main options
1. Roaming with your home plan
The simplest option is to keep using your home carrier. Some plans include roaming in certain countries, and many carriers sell daily or weekly roaming passes. The advantages are that nothing changes on your phone and your number works as normal. The risk is cost: roaming without a plan or pass can be very expensive. Before you travel, check exactly what your plan includes in the US, or abroad if you are an American traveling overseas.
2. An eSIM
An eSIM is a digital SIM card that you download onto your phone rather than inserting a physical card. Many travelers now buy a data-only eSIM from an eSIM provider before they leave, choosing a plan by data amount and number of days. You install it at home over Wi-Fi, then switch it on when you land.
To use one, your phone must support eSIM and must be unlocked, meaning your home carrier allows it to use other networks. Most recent smartphones support eSIM, but check your model's settings and confirm the lock status with your carrier before buying anything.
3. A local prepaid SIM
You can also buy a prepaid SIM card or eSIM from a US carrier at its stores and at many electronics and convenience stores. This gives you a local number, which can be handy for calling restaurants or tour companies, and plans often include generous data. It takes a little more effort on arrival and also requires an unlocked phone.
Keeping your home number
Many banks and services send login codes by text message to your home number. If you swap your physical SIM out, you may not receive them. Phones that support both a physical SIM and an eSIM can run two lines at once: keep your home line active for calls and texts but turn off data roaming on it, and use the travel eSIM for data. Check your carrier's charges for receiving texts abroad, which are often free but not always.
Setting it up: a short sequence
- Check that your phone is unlocked and supports eSIM.
- Buy and install your eSIM at home, on reliable Wi-Fi, and save any instructions offline.
- Before the flight, set the travel line as your data line and turn off data roaming on your home line.
- On landing, switch the travel line on and confirm it connects before leaving the airport.
Arriving with working data makes the trip into town much easier; our guide to airport-to-city transfers covers the options in San Francisco and Boston.
Using Wi-Fi well
Free Wi-Fi is widely available in US cities: in hotels, cafes, libraries, many museums and most major airports, including SFO and Logan. It is useful for large downloads and video calls, which can eat through a data plan quickly. A few precautions are sensible on public networks:
- Make sure you are joining the official network; ask staff for the exact name.
- Avoid banking or entering sensitive details on open networks, or use a trusted VPN.
- Turn off automatic joining of open networks and file sharing.
- Keep your phone's software updated before you travel.
Plan for no signal
Even in a well-connected country, there are dead spots. Coverage drops in some subway tunnels, in deep canyons such as the redwood valley at Muir Woods, and along remote stretches of coast such as parts of the Pacific Coast Highway. Before setting out:
- Download offline maps for the city and any day-trip areas.
- Save tickets, booking confirmations and hotel addresses as screenshots or offline files.
- Note an emergency contact and your hotel's number on paper.
Battery and safety
Navigation, photos and constant searching drain batteries fast. Carry a small power bank and a short cable. For those traveling alone, a working phone is also a safety tool, so keep it charged and share your plans with someone at home; our guide to solo city trips has more. In the US, the emergency number is 911, and it works from any phone.
Frequently asked questions
Will my phone work in the US?
Most recent smartphones work on US networks. Older or regional models may lack some frequency bands, so check your model's specifications if it is several years old.
Can I make calls with a data-only eSIM?
Not normal phone calls, but internet calling and messaging apps work over data. Your home line can still receive calls if it stays active.
How much data do I need?
It depends on use. Maps and messaging use little; video and uploading photos use a lot. Check your phone's data usage at home for a typical week as a guide.