Getting a US phone number: which number your bank will accept

Open an account in the US, apply for a credit card or sign up with a government agency online, and sooner or later you hit the same field: phone number. A European number often gets you further than you think there, and sometimes nowhere at all. In America, your number isn't just a way to reach you. It's a key to your accounts.

This guide explains how a US number is structured, what kinds of numbers exist, why banks and agencies often reject internet numbers, how secure text message codes are and how to keep your number when you don't live in the US. It names no providers. It draws on the rules of the FCC, the US telecommunications regulator, on federal agency guidelines and on public statements from the services themselves. For the other documents an account opening requires, see the guide Documents for opening an account.

1Why your bank wants your number

The FCC puts it this way in its consumer guidance: your mobile number can be the key to your most important financial accounts. Banks, businesses and payment services send text messages to verify your identity when you log in or change account details. Whoever controls your number can reset passwords and take over accounts. That's exactly why banks care which number you give them.

What the rules don't require is just as interesting. Under 31 CFR 1020.220, a US bank must collect four pieces of information before opening any account: name, date of birth, address and an identification number, which for foreigners might be a tax ID or a passport number with the issuing country. A phone number isn't on the list. When a bank demands a US number, that's its own policy for security and reachability. Every bank can handle it differently, and none has to explain why it won't take a particular number.

For you, that means a suitable US number isn't a formality. It's part of the same preparation as your address. If you're setting up an account from abroad, plan for it from day one.

2How a US number is structured

A US phone number has ten digits in the format NXX-NXX-XXXX. The first three digits are the area code, officially the Numbering Plan Area. The next three are the Central Office Code. The last four are the line number. By the FCC's definition, N stands for a digit from 2 to 9 and X for a digit from 0 to 9. So an area code never starts with 0 or 1, and the same goes for the Central Office Code.

On forms you'll usually write the number as (512) 555-0100 or 512-555-0100. Calling from Europe, you dial +1 first. That country code doesn't belong to the US alone. Under FCC rules, the North American Numbering Plan, the numbering system the US belongs to, also covers Canada and a number of Caribbean nations, including the Bahamas, Jamaica and the Dominican Republic. So a +1 number isn't automatically a US number. If a form specifically asks for a US number, a Canadian one won't do.

The area code stands for the numbering region where the number was issued. According to the FCC, if you later move to another region and switch providers, you can't always take your number with you. An area code from your future hometown is nice, but what counts most for bank and agency checks is the type of line.

3Mobile, landline, internet: three kinds of numbers

For banks, the type of line matters more than the area code. A mobile number is tied to a SIM or eSIM, meaning a contract with a carrier and a device. A landline number is tied to a physical line and can't receive texts. That's why Login.gov, for example, delivers codes to landlines by phone call.

The third type is the internet number. The FCC calls these services interconnected VoIP: voice services over a broadband connection that let you receive calls from and make calls to the public phone network. Under FCC rules, these providers can obtain numbers from the numbering plan directly. So a VoIP number is a real phone number, but it isn't tied to a SIM or a location. The FCC notes that some VoIP services let you pick an area code that doesn't match where you live, and that 911 calls over VoIP may be limited if the service doesn't know your location.

That very freedom is what makes internet numbers attractive to travelers. And it's exactly what makes some banks and agencies suspicious.

4Why banks and agencies reject internet numbers

The clearest public statement comes from a federal agency. Login.gov, the US federal government's sign-in service run by the General Services Administration, checks your phone number against public and private records during identity verification and sends you a code to confirm the number is yours. The number must be issued in the US. According to Login.gov, it doesn't accept international numbers, VoIP numbers, premium-rate numbers or most prepaid numbers.

The reason lies in the logic of the check. A contract mobile number can be linked to a person; an internet number you can set up in minutes often can't. The US standards institute NIST long wrote this view into its digital identity guidelines: the 2017 version, SP 800-63B, explicitly barred methods that don't prove possession of a specific device, such as VoIP and email, from being used for out-of-band verification. The current version, SP 800-63-4, dropped that ban. But it still classifies verification over the phone network as restricted and advises verifiers to look for warning signs such as a device change, a SIM swap or a number port before sending a code.

For you, that boils down to a simple rule. Whether a bank accepts a VoIP number is up to the bank. A mobile number in your name is the option that passes the most checks. A VoIP number may be fine for callbacks and business contacts, but it's not the number your accounts should depend on.

5Text messages are the weakest link

Even the best mobile number has one weakness: the text message itself. In its mobile communications guidance, CISA, the US cybersecurity agency, recommends moving away from SMS as a second factor. Texts aren't encrypted, anyone with access to a carrier's network can read them, and they don't protect against phishing. Login.gov says codes by text or phone call are convenient but highly vulnerable to theft and attacks.

That's why many services offer safer methods: an authenticator app that keeps generating new codes, a passkey on your device or a security key. Mercury, for example, requires at least one authenticator app for every business account and considers those codes more secure than texts. For what else Mercury requires from a US LLC, see the guide Mercury for your US LLC.

Your phone number doesn't disappear, though. CISA points out that some services fall back on SMS for account recovery. If you set up an authenticator app, check whether texting remains as a backup route. Your number stays the emergency key to your account, and an emergency key has to work when you need it.

6From your home country

The easiest way is to carry your US number on your own phone. The FCC explains that many devices have an eSIM alongside a removable SIM and can run two separate numbers on one device, such as a personal and a business line. The eSIM is built into the device, is set up in the settings and, according to the FCC, can't be stolen without stealing the phone. Your home number stays active, and the US number runs alongside it.

Clear up two things before you sign up. First, whether the plan receives texts while you're outside the US, because that's exactly where you'll need your bank's codes. Second, what information the provider requires for the contract. For text codes, any number that reliably receives messages will do; for identity verification with agencies, what counts is that it can be linked to you.

A number tied to a real US residential address strengthens that link. For a personal account without US residency, US Bank Account Opening bundles the account, address and phone line.

7Keeping the number alive

The biggest risk to your US number isn't a hacker, it's forgetting. On prepaid plans, the number depends on your balance. One major US carrier's terms, for example, require you to pay within 60 days after your balance expires; otherwise the account is closed and the number is gone. Other carriers have other deadlines, and your own terms are what count. Auto top-up is the simplest safeguard.

What happens next is governed by FCC rules. A disconnected number first goes into a waiting period called aging. For residential customers it lasts at least 45 and at most 90 days; for business customers at least 45 and at most 365 days. After that, the number can be assigned to someone else. If it's still on file with your bank, the codes for your account go to a stranger.

If you switch carriers, your number comes with you. Under FCC rules, your current carrier cannot refuse to port it, even if you still owe money. Simple ports must be completed within one business day under FCC rules. Never cancel your old plan before the new one is up and running, or you risk exactly the gap in which the number gets lost.

8Protecting yourself from SIM swaps and port-out fraud

The FCC describes how port-out fraud works without mincing words. Scammers gather personal data from social media or buy it, use it to convince your carrier to move the number to another device or account, and then try to reset as many accounts as possible with the intercepted codes before the victim notices their phone has lost service. That is why the FCC adopted rules requiring carriers to verify a customer's identity using secure methods before a SIM swap.

The FCC sums up what you can do yourself in a few steps. Set up a PIN or password with your carrier for any requests about your account. Turn on email and text alerts for your financial accounts. Never give personal details over the phone to anyone claiming to be your carrier or your bank; call back on a number you know. And keep details like your date of birth or the last digits of a Social Security number off social media.

If your phone suddenly loses service, the FCC advises you to contact your carrier and your bank right away, file a police report and place a fraud alert with the credit bureaus. If you live abroad, you often notice a dead US number later. So a quick check that the number still receives texts belongs in every routine.

9A number that matches your address

In the end, your phone number is one building block of your identity in the US, alongside your address, tax ID and credit history. Banks and agencies check whether these pieces fit together: the same person, the same address, a number that can be tied to you. An internet number pointing to an address in another state, or a prepaid number that belonged to someone else yesterday, doesn't fit that picture well.

So plan your number together with your account and address, not afterwards. How the address fits in and what else a bank wants to see is covered in the guides Documents for opening an account and Your first bank and credit after the move. How a credit history grows from there is shown in the guide US bank account and US credit. The bank decides on every account, the issuer on every card. Your number only decides whether their code reaches you.

In short

• Banks and services use your phone number to verify your identity; US account-opening rules don't require it, but the institutions themselves do.
• A US number has ten digits in the format NXX-NXX-XXXX; Canada and parts of the Caribbean share the same +1 country code.
• Login.gov, the US federal government's sign-in service, does not accept VoIP numbers or most prepaid numbers for identity verification.
• NIST and CISA consider SMS a weak second factor; an authenticator app is safer wherever the service offers one.
• A lapsed number can go to someone else within a few weeks, so keep it active and protect it with a PIN at your carrier.

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