eSIMs, SIM cards and phone service for visitors

Most visitors arrive in Palo Alto with a smartphone that already works on American networks. The real question is cost. Roaming on a home plan can be expensive, depending on your carrier, while a travel eSIM bought before departure is often cheaper for data. A US SIM card from a local store is a third route and the only one that reliably gives you an American phone number.

This page explains the three options, how to check your phone before you leave, where to buy service in town and where to get online for free. For the wider arrival basics, such as entry rules, money and tipping, see our guide for international visitors.

Roaming, eSIM or US SIM: the three options

Many travelers combine two of these. A common setup keeps the home SIM switched on for texts and banking codes while a travel eSIM handles data. Apple's support page on using eSIM while traveling notes that your primary line keeps working if you leave both lines on. iMessage and FaceTime also continue on your home number when you use only the travel eSIM. Choose the travel line for cellular data so your home line does not run up roaming charges.

Check your phone before you go

Is it unlocked?

A phone bought on contract may be locked to its original carrier. A locked phone cannot use another company's SIM or eSIM. On an iPhone, go to Settings, then General, then About and look for "No SIM Restrictions" next to Carrier Lock. On Android phones the menu names vary by maker. If your phone is locked, ask your home carrier to unlock it well before you travel.

Does it support eSIM?

Most flagship phones from recent years support eSIM, as do many mid-range models. Check your phone's settings for an option to add an eSIM or a cellular plan. Some iPhone models sold in certain markets are eSIM only, with no physical SIM tray. Apple also lists exceptions, such as the rule that iPhones bought outside China mainland cannot use an eSIM from a China mainland carrier.

Will it work on US networks?

The three national networks are AT&T, T-Mobile and Verizon. All three shut down their 3G networks in 2022, according to the FCC's 3G phase-out guide. The FCC warned that many older phones can no longer make or receive calls and texts on US networks, including calls to 911. If your phone is several years old, make sure it supports 4G LTE with voice calling (often called VoLTE) on US bands.

Travel eSIMs

A travel eSIM is a digital SIM profile you buy online and install with a QR code or an app. You can set it up at home on Wi-Fi, then switch it on when the plane lands at SFO or San Jose. Plans are usually sold by data allowance and number of days.

Several companies sell US eSIMs this way. You can browse US eSIM packages on Airalo, compare Saily's US data plans or look at Yesim's US options. GigSky and Drimsim also sell travel data. Before you buy, check four things on the plan page:

• Data only or with a number. Many travel eSIMs give you internet but no US phone number. You can still call and message over WhatsApp, FaceTime or similar apps.
• Which network it uses. Coverage differs by carrier in the hills west of Interstate 280 and on the coast.
• Validity. Check whether the clock starts when you install the eSIM or when it first connects.
• Hotspot use. If you plan to share data with a laptop, make sure tethering is allowed.

T-Mobile's U.S. Pass

The carriers now court visitors directly too. In May 2026 T-Mobile Prepaid launched U.S. Pass eSIM plans for international travelers. At launch it priced them at $25 for 7 days, $30 for 10 days, $35 for 14 days and $50 for 30 days. Every tier included unlimited talk and text in the US, Mexico and Canada plus unlimited 5G data in the US, with 50 GB of premium data and a hotspot allowance from 14 GB to 50 GB. T-Mobile described the offer as limited time and subject to change, so check its current terms before you count on it.

Buying a SIM in Palo Alto

If you would rather talk to a person, the carrier stores downtown are a short walk from the Palo Alto Caltrain station. Our guide to internet and cell service lists them in detail.

• T-Mobile University Ave & High St, 165 University Avenue. T-Mobile lists it as an Experience Store and its store page includes T-Mobile Prepaid.
• AT&T at 479 University Avenue plus AT&T Page Mill at 2805 El Camino Real.
• Verizon authorized retailers run by Victra at 222 University Avenue and 2999 El Camino Real.

Bring your passport and an unlocked phone. Apple notes that some local plans may require identification such as a passport. Store hours vary by day, so check each carrier's store page before you go. If you also need a charger or a plug adapter, our electronics and tech guide covers shops in town.

Coverage around Palo Alto and Stanford

On the flat part of town, from the Baylands to El Camino Real and across the Stanford campus, all three networks generally work as you would expect in a dense suburb. Signals get patchier in the foothills. Hills and canyons along Page Mill Road, Skyline Boulevard and parts of the open space preserves can block service. If you plan to hike at Foothills Nature Preserve or drive to the coast, download offline maps first. Large concrete buildings, including some hospital and lab buildings, can also weaken the signal indoors. Turn on Wi-Fi calling if your plan supports it.

Free Wi-Fi

You can get a long way on free Wi-Fi, especially in the first hours after landing.

• SFO. The airport's Wi-Fi page says free service covers all terminals. Join the network named #SFO FREE WIFI and open a web browser to accept the terms.
• Caltrain. Caltrain says its electric trains offer free Wi-Fi and charging outlets at nearly all seats. Our Caltrain guide covers fares and tapping on.
• Palo Alto City Library. All branches offer free Wi-Fi on the network PA_OverAir_Library with no password. Sessions last two hours and you can reconnect.
• Stanford. The open Stanford Visitor network works across campus. You accept the terms in a browser and sessions last up to 12 hours with limited bandwidth.
• Cafes and hotels. Most cafes downtown and on California Avenue offer Wi-Fi to customers. Hotels usually include it.

We did not find a citywide outdoor Wi-Fi network on the City of Palo Alto's website, so do not count on Wi-Fi in parks or on the street. Our page on free Wi-Fi and computers has the details, including printing a boarding pass at the library. On any public network, use sites that start with https and avoid logging in to your bank.

Calls, numbers and 911

US phone numbers have ten digits: a three-digit area code and a seven-digit number. Palo Alto and most of the Peninsula use the 650 area code. From a foreign phone, dial +1 before the full number. Toll-free numbers start with 800, 888, 877 and similar codes. If one will not connect from your foreign number, try the company's website or app.

For police, fire or an ambulance, dial 911 from a phone that works on US networks. If you are staying at a hotel, note the street address so you can give it to the dispatcher. For medical problems that are not emergencies, our guide to urgent care and emergency rooms lists local options. It also helps to arrange visitor health insurance before you travel, since US care is expensive.

Set it up before you fly

1. Check the lock. Confirm your phone is unlocked and supports eSIM, or that you have a SIM tray for a physical card.
2. Price your roaming. Look up your home carrier's US rates and daily passes so you can compare.
3. Buy and install early. Install a travel eSIM at home over Wi-Fi, but leave it switched off until you land if the plan starts on installation.
4. Label your lines. Name them "Home" and "Travel" in settings and set the travel line for data.
5. Save offline maps. Download the Bay Area in your map app for the drive or train ride from the airport.
6. Note key numbers. Save your hotel's phone number and address. Keep your airline's app logged in.
7. Pack a plug adapter. US outlets use types A and B at 120 volts.

Frequently asked questions