45 terms you will meet when you get a US number from abroad, from area codes to VoIP, in a sentence or three each.
This glossary explains the phone terms that come up when you get a US number from outside the US: how US numbers are built, the types of numbers and lines, verification and security, and calling across time zones. Each term links to a page that goes deeper.
The first three digits of a 10-digit US number, such as 212 in (212) 555-0123. In the numbering plan it is called the NPA. It tells people roughly where a number comes from, although many numbers no longer live where their area code suggests.
An app, such as Google Authenticator or Microsoft Authenticator, that shows a new six-digit login code every 30 seconds. It works without a phone number or signal, so it does not break when you change numbers or travel.
A setting that sends incoming calls on one number to another number. Carriers and some apps charge for forwarded calls, especially when the second number is abroad.
Caller ID is the number shown when someone calls you. CNAM is the US database that adds a caller name to that number. Name display depends on the receiving carrier, so a business name is not shown everywhere.
A mobile network operator that runs its own cell network, such as AT&T, T-Mobile or Verizon in the US. A carrier number is tied to a SIM or eSIM on that network, and lookup databases label it as mobile.
The international prefix for the US, Canada and the other countries that share the North American Numbering Plan. From abroad you dial your exit code or +, then 1, then the 10-digit number.
A travel eSIM that gives you mobile data but no phone number. You get internet in the country you visit; calls and texts to a number then need an app over that data.
Most of the US moves its clocks one hour forward on the second Sunday in March and back on the first Sunday in November. Hawaii and most of Arizona do not change. If your country changes on different dates, the gap to US time shifts for a few weeks.
A phone number that routes calls straight to a person, app or phone system over the internet, without a separate physical line. Most virtual numbers are DIDs.
A phone that holds two lines at once, using two SIM cards, a SIM and an eSIM, or two eSIMs. It lets you keep your home number active while you add a second plan.
The international standard way to write a phone number: a plus sign, the country code and the full number with no spaces, up to 15 digits. A New York number looks like +12125550123. Many sign-up forms expect it.
A SIM built into the phone that you install by scanning a QR code instead of inserting a card. It can carry a carrier plan with a number, or a data-only plan.
The prefix you dial to leave your own country's phone network before the country code. It is 00 in most of the world and 011 from the US and Canada. On a mobile phone you can type + instead.
A limit that stops an "included" allowance from being used without end. For example, incoming calls on the TripoSIM number are included with a fair-use limit of 300 minutes a month.
An internet phone service tied to one address, such as a home or office phone line from a cable or internet provider. Lookup databases often treat it more like a landline.
iMessage is Apple's messaging service between Apple devices. RCS is the newer messaging standard that adds typing indicators, photos and read receipts to texting on Android and recent iPhones. Both are separate from plain SMS.
"Know your customer": checking who you are before giving you a service, usually with a photo ID and a selfie. The TripoSIM number asks for one before you choose a number.
A database check that tells a service whether a number is mobile, landline, fixed VoIP or non-fixed VoIP. Some apps run it at sign-up. The TripoSIM number still receives verification codes from apps, including WhatsApp.
An ordinary 10-digit phone number, as opposed to a 5- or 6-digit short code. Businesses use long codes for calls and person-to-person style messages.
Multimedia messaging: texts with photos, video, audio or long text, carried over the mobile network. Not every virtual number receives MMS.
A mobile virtual network operator: a phone company that rents capacity on a carrier's network instead of running its own, such as Mint Mobile or Visible in the US. Its numbers are usually labelled mobile.
The North American Numbering Plan: the shared +1 numbering system of the US and its territories, Canada and many Caribbean countries. Every NANP number has a 3-digit area code, a 3-digit exchange and a 4-digit line number.
An internet phone number you can use from anywhere with internet, through an app. App numbers, including the TripoSIM number, are non-fixed VoIP. The TripoSIM number receives verification codes (OTP SMS) from apps, including WhatsApp.
A number a lookup database labels as mobile or landline from a phone company, rather than VoIP.
Moving a number you want to keep onto a cheap service that holds it without a full phone plan. People park a US number before moving abroad so they do not lose it.
Moving your existing number from one provider to another. In the US the FCC requires carriers to let you keep your number when you switch, as long as you stay in the same area and the account is active.
Giving a disconnected number to a new customer after a waiting period. If accounts still point to your old number, the new owner can receive your codes.
A one-time passcode, usually 4 to 8 digits, that a service delivers by text, call or email to confirm it is you. Each code expires after a few minutes.
A second area code added to the same region when the first runs out of numbers, such as 332 over 212 in Manhattan. Numbers on both codes are equally local.
A login that uses your phone or computer's screen lock (face, fingerprint or PIN) instead of a password and code. It is tied to your device, not your phone number.
The small removable card that connects a phone to a carrier's network and carries its number. Swapping it for another card changes your active line.
A number that can get texts but cannot answer them. The TripoSIM number receives texts from US and Canadian senders; sending texts is not included.
Using your home carrier's line on a foreign network. Calls, texts and data while roaming are often charged per minute or per day. An app number over Wi-Fi or local data does not use roaming.
A 5- or 6-digit number that businesses use for bulk messages such as alerts, marketing and login codes. Some short codes only deliver to carrier mobile numbers.
A plain text message of up to 160 characters per segment, carried over the phone network. It is the format most verification codes use.
Warnings such as "Spam Likely" that US carriers and apps show on incoming calls they think are unwanted. New numbers that call many people quickly are the most likely to be labelled.
The caller ID authentication system US carriers use to check that a call really comes from the number shown. The FCC requires it to fight spoofed robocalls.
A US number starting 800, 833, 844, 855, 866, 877 or 888, where the business pays for the call. Many toll-free numbers cannot be reached from outside the US, or cost a normal international rate.
Extra calling minutes bought on top of a plan. On the TripoSIM number they cost $5 per 100 minutes. Top-up minutes are used after your monthly minutes, stay valid while your number is active and carry over when you renew. They are not refundable.
A login that needs a second proof after your password, such as a code by text, an authenticator app or a passkey. Text codes are the weakest option because they depend on keeping the same number.
The four main mainland zones: Eastern (UTC−5, or UTC−4 in summer), Central (UTC−6), Mountain (UTC−7) and Pacific (UTC−8). Alaska and Hawaii are one and two hours behind Pacific.
A phone number that is not tied to a SIM card or a physical line. You use it in an app or forward it to another phone, from anywhere with internet.
A recorded message a caller leaves when you do not answer. On the TripoSIM number, messages can be up to 2 minutes, up to 30 a month, kept 30 days.
A number whose calls and texts travel over the internet instead of a mobile or copper network. VoIP comes in two kinds, fixed and non-fixed. The TripoSIM number is a non-fixed VoIP number.
A carrier feature that lets your normal mobile line make and take calls over Wi-Fi when the cell signal is weak. It still uses your carrier number and plan, unlike an app number.
Two plans with the same number, minutes and app.
$100per year
About $8.33 a month, paid once a year
Renews yearly until you cancel
$12.99per month
Cancel the renewal anytime. $155.88 over 12 months
Renews monthly until you cancel
Prices in US dollars as published by TripoSIM. Payments are not refunded, except a full refund if your number is not delivered within 72 hours, or where local law requires. Checkout continues on TripoSIM. Right after payment you complete an ID check with a selfie, then choose from the numbers available.