Before you start

An unlocked handset, or an eSIM-capable one
A US address for postpaid, but not for prepaid
A payment method — prepaid accepts foreign cards, postpaid usually does not

Step-by-step

1
Activate an eSIM before flying, or buy prepaid on arrival
A US eSIM activates before you land so you have a working number immediately for rides, deliveries and bank verification codes. No identity registration is required at any point.
OnlineWho: YouDay 1
2
Check your handset is unlocked and band-compatible
Phones bought on contract abroad are frequently locked, and US band combinations trip up some regional models. With 3G shut down there is no fallback network to land on.
OnlineWho: You
3
Start prepaid rather than fighting a credit check
Postpaid runs a credit check. With no US file you will be declined or asked for a deposit. Prepaid has no check and is usually cheaper for the same data allowance.
OnlineWho: You
4
Enable Wireless Emergency Alerts and register for the county alert system
Federal wireless alerts cover evacuation and severe weather warnings automatically. Riverside County also runs an opt-in emergency alert programme that is far more granular and is what reaches you first in a canyon fire or a local evacuation. Sign up for both in your first week.
Mobile appWho: YouWeek 1
5
Set your power account up with the city, not with Edison
Riverside Public Utilities is the city's own electric and water utility. Outage maps, high-bill alerts and payment arrangements all come from the city rather than from the investor-owned utility serving surrounding areas. Register on the city's utility portal in week one so outage notifications actually reach you.
OnlineWho: YouWeek 1
6
Prepare for red-flag days and heat events
Santa Ana wind events drive the region's worst fire weather, and summer heat here regularly exceeds 38°C. Keep a charged power bank, know your address's fire hazard severity zone on the state fire marshal's map, and remember that a home router without power takes your Wi-Fi calling with it. If you commute long distances, keep a car charger and water in the vehicle as a habit.
OnlineWho: You
7
Check signal along the commute, not just at home
The Santa Ana Canyon on the 91 and the passes east of the city have genuine coverage gaps. If you rely on navigation, hands-free calls or a rideshare app on that route, test it on the actual road before you depend on it — and download offline maps for the canyon stretch.
In personWho: You
8
Port rather than cancel if you switch later
Number portability is a legal right and works between carriers and MVNOs. Request the port from the new carrier — never cancel the old service first, or you lose the number.
OnlineWho: You

Documents you’ll need

Passport for postpaid; nothing at all for prepaid
US address for postpaid
A payment card — prepaid usually accepts foreign cards, postpaid rarely does

Things most newcomers don’t know

Your utility is the city, which changes who you call and who alerts you.

Riverside Public Utilities has supplied the city's electricity and water since 1895 and is one of very few municipal utilities in Southern California. Every generic Southern California guide tells you to open a Southern California Edison account, which is simply wrong at a Riverside address. It also means outage alerts, rebates and payment plans are city programmes — worth registering for in week one rather than during an outage.

Source: Riverside Public Utilities

The county alert system reaches you before the federal one does.

Wireless Emergency Alerts are broadcast to a wide area and fire only for serious, imminent threats. The county's opt-in system can target a specific canyon or street with an evacuation warning well before a federal alert would fire. In the hillside neighbourhoods that lead time is the whole point.

Source: community-reported

The credit check is the barrier, not the documentation.

Carriers check credit before offering postpaid, and a newcomer with no file gets declined or charged a deposit. Prepaid sidesteps it entirely and usually costs less for the same data.

Source: community-reported

The US has no SIM registration at all.

Most countries in this app require passport registration to activate a SIM. The US requires nothing whatsoever for prepaid — you can buy one in a supermarket and be online in minutes.

Source: FCC — consumer guides

Common mistakes to avoid

Trying to open a Southern California Edison account at a Riverside address.
Assuming Wi-Fi calling will cover a weak indoor signal during an outage.
Applying for postpaid with no credit file and facing a large deposit.
Silencing emergency alerts after one loud test, in a fire region.
Relying on a live navigation app through the Santa Ana Canyon without offline maps.
Cancelling the old carrier before requesting the port, and losing the number.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.