Glossary
What is E.164 format?
E.164 is the international format for phone numbers: a plus sign, the country code, then the national number, with no spaces or punctuation and no more than 15 digits. A US number like (415) 555-0132 is written +14155550132.
The parts of an E.164 number
| E.164 | The ITU-T recommendation that defines the international public telephone numbering plan, including how a full international number is written. |
| Country code | The 1 to 3 digit prefix that identifies the country or region, for example 1 for the US and Canada, 44 for the UK, 61 for Australia. |
| National number | The rest of the number after the country code. In the US this is the 3-digit area code plus the 7-digit local number. |
| 15-digit limit | An E.164 number has at most 15 digits, counting the country code but not the plus sign. |
| Trunk prefix | A leading digit some countries use for domestic dialing, such as the 0 in UK numbers. It is dropped in E.164. |
E.164 examples
| Country | As dialed locally | E.164 |
|---|---|---|
| US | (415) 555-0132 | +14155550132 |
| Canada | 416-555-0199 | +14165550199 |
| UK | 020 7946 0018 | +442079460018 |
| Australia | (02) 5550 1234 | +61255501234 |
Not sure of a country code? Use the free country code lookup.
How to convert a US number to E.164
- Remove spaces, dashes, dots, parentheses and any extension.
- If 10 digits are left, put +1 in front.
- If 11 digits are left and the first is 1, put + in front.
- Any other length is not a complete US number. Flag it instead of guessing.
The free phone number formatter does this for a pasted list, removes duplicates and flags bad formats. For a whole file, use the CSV phone number normalizer.
Formatted is not the same as reachable
- Format: E.164 makes every number look the same, which makes duplicates easy to find and keeps APIs happy.
- Validity: a well-formatted number can still be disconnected or never assigned.
- Line type: the format does not tell you whether a number is mobile, landline or VoIP. A live carrier lookup does.
What TrueSearch returns, and does not
| Valid or dead (disconnected / not assigned) | Yes, every number |
| Line type: mobile, landline, VoIP, toll-free | Yes, every number |
| Carrier name | Yes, every number |
| Bulk upload (CSV or Excel) | Yes, results in about 30 seconds per 1,000 numbers |
| REST API | Yes (JSON, one API key) |
| Claude / ChatGPT / Cursor connector (MCP) | Yes |
| National or state Do Not Call check | No, not yet |
| Known TCPA litigator check | No, not yet |
| FCC Reassigned Numbers Database check | No |
| Starting price | $97/month for 5,000 numbers, 7-day free trial |
| One-off list | $20 per 1,000 numbers, no subscription |
Upload a CSV or Excel file. Every number comes back valid or dead, mobile, landline, VoIP or toll-free, with its carrier.
Starter: $97/month for 5,000 numbers after the 7-day trial. Cancel anytime.
Questions
What is E.164 format?
E.164 format writes a phone number as a plus sign, the country code and the national number, with no spaces, dashes, parentheses or leading trunk zero. It can be at most 15 digits. A US number like (415) 555-0132 becomes +14155550132.
How do I convert a US number to E.164?
Strip everything that is not a digit. If you have 10 digits, add +1 in front. If you have 11 digits starting with 1, add a plus sign. Anything else is not a complete US number. The free phone number formatter does this for a whole list at once.
Does E.164 include the plus sign?
The plus sign is how E.164 numbers are written for display and in most APIs and CRMs. It is not counted in the 15-digit limit.
Why do CRMs and SMS tools ask for E.164?
One fixed format means every copy of a number looks the same, so duplicates are easy to spot and numbers route correctly across countries. Many SMS and calling APIs require E.164 for the to and from numbers.
Does E.164 format mean the number works?
No. E.164 only describes how the number is written. A perfectly formatted number can still be disconnected, a landline or a VoIP line. A live check tells you whether it is valid and what line type it is.
Does TrueSearch return numbers in E.164?
TrueSearch accepts US numbers in common formats and returns whether each is valid, its line type and its carrier. To convert a list to E.164 for free, use the phone number formatter, which runs in your browser.
Does TrueSearch check Do Not Call status?
No. TrueSearch checks validity, line type and carrier only. For Do Not Call status, use the National Do Not Call Registry at donotcall.gov.
Related: what is phone line type?, what is a ported number?, what is a VoIP number?, free phone number formatter and carrier lookup.
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This guide is general information, not legal advice. TrueSearch for Business checks validity, line type and carrier from licensed telecom data. It does not check the National Do Not Call Registry, state DNC lists or the FCC Reassigned Numbers Database. Not a consumer reporting agency; not for FCRA purposes.