E.164 Format

E.164 defines a general format for international telephone numbers for calls that go out through the public switched telephone network number (PSTN). This allows phone calls and text messages to be correctly routed to phones in different countries.

E.164 formatted telephone numbers start with the Country Code followed by the Global Subscriber Number.


When using one of Ytel's API Endpoints, which requires a phone number, it is important to ensure the number is using the E.164 format. This may require the use of programmatically appending a "+" and the appropriate country code when capturing a customers phone number as well as verifying the telephone number is valid. Our Carrier Lookup API is a great tool to use for validating telephone numbers.

Example telephone numbers in E.164 format

E.164 Format

Country Code

Subscriber Number

+1 555 222 1111

1 (US)

555 222 1111

+44 555 222 1111

44 (UK)

41 555 222 1111

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