Mobile Phone Number Format

Mobile numbers used within all Kaleyra products should conform to the standards specified by the International Telecommunication Union – Telecommunication Standardization Sector (ITU-T) in the E.164 recommendations.



E.164 numbers are formatted [+] [country code] [subscriber number including area code] and can have a maximum of fifteen digits.

For more information, consult the E.164 recommendations.

  • All US mobile numbers should be prefixed with β€œ1” before the area code and phone number; for example, 12565551212. The "1" represents the country code for the US.
  • All non-US mobile numbers must be prefixed with the country code.
  • Numbers without a country code may be accepted but will not be guaranteed to work in all scenarios.