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.
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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
Leave the weather alerts on — including the winter ones
Wireless Emergency Alerts carry blizzard and winter storm warnings and extreme cold warnings as well as summer tornado and flash flood warnings. In Milwaukee the winter ones are the ones that will actually change your day, and a snow emergency declaration also changes where you may legally park.
Mobile appWho: YouWeek 1
5
Shop home internet by address
Cable covers essentially the whole city and fibre availability varies street by street in the older neighbourhoods. Check the address on the FCC's broadband map before signing a 12-month term, and ask the building rather than the provider what actually gets installed — older duplexes sometimes have wiring constraints the availability map does not know about.
OnlineWho: You
6
Carry a battery bank in winter
Cold reduces lithium battery capacity substantially, and a phone that lasts all day in July will not in January. A pocket battery bank and keeping the phone in an inside pocket rather than an outer one are the two practical fixes, and both matter if you are waiting for a bus.
In personWho: You
7
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

The alerts that matter here are the winter ones.

In most cities in this app the emergency alert you must not silence is a tornado or flood warning. In Milwaukee it is a winter storm or extreme cold warning — and a declared snow emergency changes the parking rules on your street the same night. Leave the whole category on.

Source: FCC — Wireless Emergency Alerts

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

Check what the building can actually take, not just what the map says.

Broadband availability maps report what a provider serves at an address, not what the wiring in a hundred-year-old Cream City duplex will support. Ask the landlord what the last tenant had and what was installed, before you commit to a service tier you cannot receive.

Source: FCC — National Broadband Map

Common mistakes to avoid

Applying for postpaid with no credit file and facing a large deposit.
Bringing a carrier-locked handset from abroad and discovering it on arrival.
Silencing weather alerts and missing a snow emergency that changes where you may park.
Assuming a broadband availability map reflects what an old duplex can actually take.
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.