Using an eSIM in San Francisco

What San Francisco is like on a phone

San Francisco is a walkable city packed onto the tip of a peninsula, and the people who come are split between sightseers and travellers flying in for tech meetings — both lean on the phone hard, in different ways. In town the line is good and steady, except where a steep hill puts itself between you and the nearest mast, which happens more often here than in a flat city. The clearest change comes when the rail system goes underground, both beneath Market Street and in the tube across to Oakland. Plan around those two facts and the rest of the city looks after itself.

到着後にすること

Most international flights land at SFO's international terminal, boarding areas A or G, while some routes use Oakland (OAK) or San Jose (SJC) instead. Turn the eSIM line on in the immigration queue and confirm that data roaming is enabled for it before you leave the building. BART has a station inside the airport and runs straight into town; the above-ground stretch behaves normally, but once the train drops underground on the approach to the centre the line cuts in and out. If you are collecting a rental car, set the route while you are still in the garage — the exit road stacks several interchanges together, and programming an address while driving it is a poor idea.

電波が変わる場所

The core from Union Square through SoMa and the Mission is continuously usable, but the hills mean a street tucked behind a crest can be weaker than one a single block away. The Muni Metro tunnel under Market Street and BART's tube under the bay are the two places the line clearly goes, so have your route ready before you walk down the stairs. Cross the Golden Gate Bridge towards the Marin Headlands and coverage thins as soon as the houses stop. On a sold-out night at Oracle Park, speeds around the ground fall in step with the size of the crowd.

What a day here costs in data

A walking day here usually runs about 1–2GB: the distances are short but you open the map constantly, because every hill makes you reconsider the route. Business travellers use more, tethering a laptop, joining video calls and pushing files up during the day. Calling a car instead of climbing a hill also keeps an app busy from morning to night. If you plan to film from the viewpoints and upload straight away, set aside a separate chunk of the allowance for that alone.

Districts travellers ask about

• Union Square and SoMa — Hotels and the convention halls sit here, so it is the densest part of the city, yet during a large conference the speed inside the halls drops visibly.
• The Mission — Low buildings on a grid make this one of the steadiest parts of town, easy to wander for food without worrying about the map.
• Fisherman's Wharf and North Beach — The open waterfront is fine, but the cable car queue in the afternoon gets crowded enough that pages load more slowly than they should.
• Golden Gate Park and the Sunset — The western side of the city has a less crowded network, though deep in the park under heavy tree cover and out by Ocean Beach it thins in patches.

Day trips out of the city

• Muir Woods and the Marin Headlands — Under the redwood canopy and along the cliff road the line drops for long stretches, so load the map first. Parking reservation rules and opening times shift by season and by year — check the official site before you travel.
• Napa and Sonoma — The main valley roads are usable, but the small lanes climbing to the wineries further in often go quiet; agree pickup times with your driver before you head up.
• Yosemite National Park — The park holds genuinely unserved areas, and the long approach roads are quiet too, so download offline maps before you leave the city. Entry reservation rules and fees change from year to year — go by the park's own notices.