Invalid phone number

Why Nexcal marks a phone number as invalid and how to enter numbers correctly in international format with a country code.

Last reviewed: 2026-07-22

Invalid phone number

When Nexcal marks a phone number as invalid, that number cannot be called. This protects your campaign from faulty call attempts. In most cases the problem can be fixed by formatting the number correctly.

Why a number is considered invalid

Common reasons are:

  • the number does not include a country code;
  • the number contains letters, misplaced spaces or invalid special characters;
  • the number is too short or too long for the respective country;
  • leading zeros or dialing codes were combined incorrectly.

Formatting numbers correctly

Enter phone numbers in international format with a country code where possible. A detailed guide with examples is available in formatting phone numbers correctly.

  1. Start with the country code.
  2. Remove a superfluous leading zero of the national number where the format requires it.
  3. Avoid letters and invalid characters.
  4. Check the corrected number and save the contact again.

Hinweis: If many numbers from a CSV import are marked as invalid, there is often a consistent formatting problem in the source file. Correct the format centrally and import the affected records again.

For a single contact

If it is a single contact, correct the number directly and save the change. Then check whether the number is valid again.

If the number is still rejected

If a correctly formatted number remains invalid, contact support. Name your workspace and, where needed, an anonymized example of the format you used.

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