Last updated: October 25, 2026.
A US phone number has ten national digits: a three-digit area code followed by a seven-digit local number. For the international format, add country code +1. Written as +1 202 555 0147, the number contains country code 1, area code 202 and local number 5550147.
This is a fictional example. NANPA reserves 555-0100 through 555-0199 for fictional use, so the examples here are for formatting practice rather than calls or verification texts.
The same number in different formats
| Format | Fictional example |
|---|---|
| US national display | (202) 555-0147 |
| National digits only | 2025550147 |
| International display | +1 202 555 0147 |
| Compact international form | +12025550147 |
Spaces, brackets and hyphens help people read the number. An online form may accept them or ask for digits only. Follow the example beside the field rather than adding or removing digits to match its appearance.
What each part means
In the example, 202 is the area code. Within the local number, 555 is the central-office prefix and 0147 is the four-digit line number. Country code 1 sits outside those ten national digits.
NANPA gives the national pattern as NXX-NXX-XXXX. N can be 2 through 9, and X can be 0 through 9. The area code and country code have different jobs: +1 is the country calling code, not the area code.
What to enter in a phone-number form
Look at how the form handles the country before you type. A country flag by itself does not tell you whether the field expects a national or international number.
- If the country picker supplies United States (+1) and the field asks for a national number, enter
2025550147. - If one field asks for the full international number, a compact form is
+12025550147. Include country code 1 once. - If there are separate area-code and local-number boxes, enter
202and5550147. If the local part is split again, put555and0147in the corresponding boxes.
Check the field instructions or final number preview before submitting. A repeated country code or a missing digit changes the destination.
E.164 and extensions
E.164 is the international numbering plan. Software commonly represents a number with a plus sign, country code and national number, without display punctuation. Twilio's E.164 documentation explains the structure and its maximum of 15 digits.
That maximum is not a US number's required length. A US number has ten national digits, or eleven digits when you include country code 1. If a contact also gives you an extension, keep it in the extension field or separately in the contact entry. Appending it to the main phone field does not make it part of the mobile number.
What the format cannot tell you
The US shares country code +1 with Canada and other destinations in the North American Numbering Plan. Check the country and area-code assignment when you need to distinguish them. The number's classification also does not tell you where its user is physically located.
A correctly formatted number can still be unassigned, unable to receive SMS or ineligible for a particular app. Removing punctuation will not change an unsupported line type, and ten plausible digits do not establish that you control the line.
To inspect a receiving number, compare the US SMS number directory with the Canadian number listings. Check the stated country before copying a +1 number.
If a service accepts the number but its text is missing, follow the verification-code checks. If you still need to choose a service, compare the options for a US number without a physical SIM.
