Phone Number Format: US & International Guide (2026)
Complete guide to phone number formats. Learn the anatomy of US numbers (NANP), E.164 international standard, area code rules, special numbers (911, 555, toll-free), and how to format for databases, display, and dialing.
A US phone number has 10 digits: a 3-digit area code + a 7-digit local number. With the country code +1, it's 11 digits total. The international standard for formatting phone numbers is E.164, which uses a maximum of 15 digits and the format +[country code][number].
This guide explains how phone numbers are structured in the US and worldwide: the NANP system (created in 1947), area code rules, special numbers (911, 555, toll-free), international formats for 10+ countries, and how to properly format numbers for dialing, databases, and HTML links.
Anatomy of a US Phone Number
+1 (212) 555-1234
| Component | Digits | Rules | Example |
|---|---|---|---|
| Country Code | 1 | Always +1 for US/Canada | +1 |
| Area Code (NPA) | 3 | First digit 2-9, digits 2-3: 0-9 | 212 |
| Exchange (NXX) | 3 | First digit 2-9, digits 2-3: 0-9 | 555 |
| Line Number | 4 | All digits 0-9 | 1234 |
Total: 10 digits (without country code) or 11 digits (with +1). The NANP format is NPA-NXX-XXXX, where N = digits 2-9 and X = digits 0-9.
A Brief History of US Phone Numbers
AT&T and the Bell System created the North American Numbering Plan in 1947, establishing 86 original area codes. The system was designed around rotary dial phones — high-population areas got the lowest numbers (fewest dial pulses).
| City | Area Code | Dial Pulses | Why |
|---|---|---|---|
| New York City | 212 | 5 pulses (2+1+2) | Largest city, fastest to dial |
| Los Angeles | 213 | 6 pulses (2+1+3) | Second-largest city |
| Chicago | 312 | 6 pulses (3+1+2) | Third-largest city |
| Detroit | 313 | 7 pulses | Fourth-largest at the time |
| Dallas | 214 | 7 pulses | Major Texas city |
Originally, codes with 0 as the middle digit went to single-area-code states (e.g., 203 for Connecticut), and codes with 1 went to multi-code states (e.g., 212/518 for New York). This rule ended in 1995.
International Phone Number Formats
The E.164 standard (ITU-T) defines the universal format: +[country code][subscriber number], max 15 digits.
| Country | Code | Digits | Example (E.164) |
|---|---|---|---|
| United States | +1 | 10 | +12125551234 |
| United Kingdom | +44 | 10-11 | +442079460958 |
| India | +91 | 10 | +919876543210 |
| China | +86 | 11 (mobile) | +8613912345678 |
| Japan | +81 | 10-11 | +81312345678 |
| Germany | +49 | Variable | +49301234567 |
| Australia | +61 | 9 | +61412345678 |
| Brazil | +55 | 11 (mobile) | +5511987654321 |
| Mexico | +52 | 10 | +525512345678 |
| France | +33 | 9 | +33123456789 |
Key rule: When dialing internationally, always drop the trunk prefix (leading 0). UK 020 7946 0958 becomes +44 20 7946 0958.
Special US Phone Numbers
N11 Service Codes
| Code | Service |
|---|---|
| 911 | Emergency services (police, fire, ambulance) |
| 211 | Community services and information |
| 311 | Non-emergency city/county services |
| 411 | Directory assistance |
| 511 | Traffic and road conditions |
| 611 | Phone company customer service |
| 711 | Telephone Relay Service (hearing impaired) |
| 811 | Call Before You Dig (underground utilities) |
| 988 | Suicide & Crisis Lifeline (since July 2022) |
Toll-Free Numbers
Toll-free numbers are free for callers — the receiving business pays. Area codes: 800 (1966), 888 (1996), 877 (1998), 866 (2000), 855 (2010), 844 (2013), 833 (2017).
555 Numbers (Fictional)
Numbers 555-0100 through 555-0199 are officially reserved for movies, TV, and books. This convention started in the early 1960s after viewers kept calling numbers they saw on screen.
How to Format a Number for International Dialing
From US to UK: UK domestic: 020 7946 0958 → Dial: 011 + 44 + 20 + 7946 0958. Drop the leading 0, add exit code + country code.
From US to India: India domestic: 011 2345 6789 (Delhi) → Dial: 011 + 91 + 11 + 2345 6789.
From US to Germany: Germany domestic: 030 1234567 (Berlin) → Dial: 011 + 49 + 30 + 1234567.
Tip: On a mobile phone, use + instead of 011. The + sign is universal and works from any country. Hold 0 on most phones to get +.
How to Format Phone Numbers (by Context)
| Context | Format | Example |
|---|---|---|
| Database storage | E.164 (no formatting) | +12125551234 |
| US display | Parentheses + dash | (212) 555-1234 |
| International display | + country code + spaces | +1 212 555 1234 |
| HTML tel: link | E.164 in href | <a href="tel:+12125551234"> |
| US dialing | 10 digits | 212-555-1234 |
Best practice: Always store phone numbers as strings (not integers) to preserve leading + and zeros. Normalize to E.164 on input, format for display on output.
Ready to Start Calling?
Make international calls from your browser with BubblyPhone. No app needed, instant setup.
Get Started Free →