A US phone number is one of the first things you need. Banks, schools, employers, doctors and apps send codes to it. You can get one on your first day, even without a Social Security Number (SSN).
Prepaid: you pay before the month starts. No credit check, no contract, and usually no SSN. If you stop paying, the service stops. This is the easiest choice for newcomers.
Postpaid: you use the service first and get a bill later. The carrier usually checks your credit, so without an SSN or US credit history they may ask for a large deposit or say no. Postpaid plans often come with a phone you pay for over 24 to 36 months.
Smaller carriers (often called MVNOs): companies that rent space on the networks of the big three carriers (AT&T, T-Mobile, Verizon). The coverage is the same network, the price is often lower. Most are prepaid. In busy places, their customers can sometimes get slower data than the big carrier's own customers.
These are rough ranges, not promises. Prices change often.
Smaller prepaid carriers: about $15 to $40 a month per line.
Prepaid plans from the big carriers: about $30 to $65 a month.
Postpaid unlimited plans: about $60 to $90 a month for one line, less per line for a family.
Add taxes and fees. A "$25 plan" can be about $28 to $32 on the bill, depending on your state. Many plans are cheaper if you pay for 3, 6 or 12 months at once.
If you bring a phone from home, it must be unlocked: it works with any carrier. Ask your home carrier to unlock it before you travel.
Check the carrier's website for a "bring your own phone" or compatibility checker. Type the phone's IMEI number (dial *#06# to see it).
Most phones made for Europe, Asia and Latin America in recent years work on US networks, but older or very cheap models may not.
Steps to get a plan today
Decide: prepaid (no credit needed) or postpaid (needs credit or a deposit).
Check coverage maps on the carrier sites for your home, school or work address.
Buy online (you get an eSIM in minutes) or in a carrier store, Walmart, Target or Best Buy.
Bring your passport if you buy in a store.
Choose a number with the area code (first three digits) of your city.
Save your account PIN. You need it to move your number later.
Signing a postpaid contract in week one. You may move or need a cheaper plan soon.
Choosing "unlimited" when you are on Wi-Fi most of the day. Look at your real use after one month.
Forgetting auto-pay: some prepaid plans cost $5 less with it, but then a failed card means lost service.
Buying a phone "on payments" and then wanting to leave. You must pay off the phone first, and it may stay locked to that carrier until then.