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Every recipient phone number you pass to SmsManager must include the full international dialling prefix — no local shortcuts or ambiguous national formats. SmsManager uses the E.164 standard as its canonical form, but strips the leading + sign. This means you pass a plain digit string starting with the country code, with no spaces, dashes, or other separators.

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Required format

SmsManager expects phone numbers in E.164 format without the leading + or 00. Start directly with the country code followed by the subscriber number, with no formatting characters. The pattern is straightforward: take the full international number, remove the leading +, and remove all spaces, dashes, and parentheses.

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Auto-normalization

SmsManager accepts several other common representations and converts them to the canonical format before processing. While this gives you some flexibility, passing numbers in the recommended E.164-without-+ format avoids any ambiguity and gives you the most reliable results — especially for numbers from countries that have non-obvious national dialling conventions. Formats that are automatically normalised include:
  • Numbers prefixed with a literal + (e.g. +420777123456)
  • Numbers prefixed with the international exit code 00 (e.g. 00420777123456)
  • Numbers containing spaces, dashes, dots, or parentheses as separators (e.g. 420 777 123-456)
  • National format numbers with a leading 0 where the country can be inferred (e.g. 0777123456 in some configurations)
National format with a leading 0 (e.g. 0777123456) may not be correctly identified for all countries, because the country code cannot always be inferred from the number alone. Always include the full country code to guarantee correct routing.

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Format validation table

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Country codes

Always include the full country dialling code as the first digits of the number — do not add a leading +. For example:
  • Czech Republic (420) → 420XXXXXXXXX
  • Germany (49) → 49XXXXXXXXXX
  • United States (1) → 1XXXXXXXXXX
The country code does more than just route the message — it also determines the applicable per-message price, required sender registration rules, and any country-specific content restrictions. Using the wrong or missing country code can result in misrouted messages or unexpected charges.
If you store phone numbers in your database with a leading +, strip it before passing numbers to the SmsManager API. A simple phone.replace(/^\+/, "") in JavaScript or phone.lstrip("+") in Python is all you need.

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Phone numbers in the Verify API

The Verify API accepts phone numbers in the phoneNumber field of the request body using the same format: digits only, including the country code, no leading + or 00. The Verify API validates the number against the following pattern before accepting a session request:
This means:
  • The first digit must be 1–9 (no leading zeros)
  • Total length must be between 7 and 15 digits (inclusive)
  • Only digit characters are accepted — no spaces, dashes, or +
Example Verify API request body:
Invalid phone numbers cause messages to be rejected before they are sent. A rejected message may trigger a result: rejected webhook callback. Always validate and normalise phone numbers on your side before calling the API, and check the rejected array in API responses to identify any numbers that failed.