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Documentation Index

Fetch the complete documentation index at: https://mintfax.com/docs/llms.txt

Use this file to discover all available pages before exploring further.

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Outcome

After reading this page you can format international fax numbers for the mintfax API and handle country-specific dial rules.

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Prerequisites

  • A mintfax workspace with a sandbox or live API key
  • A fax-capable document (PDF or TIFF) ready to send

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Step 1: Format numbers in E.164

Every fax number in the mintfax API uses E.164 format: a leading +, the country code, and the subscriber number with no spaces, hyphens, or parentheses.
CountryCountry codeLocal numberE.164 result
United States1(201) 555-0100+12015550100
Canada1(416) 555-0100+14165550100
United Kingdom44020 7555 0199+442075550199
Australia61(02) 5555 0150+61255550150
Drop the leading zero from the local number before prepending the country code. The UK number 020 7555 0199 becomes 2075550199 after you strip the trunk prefix 0, then +442075550199 with the country code. 
curl -X POST https://api.mintfax.com/v1/fax \
  -H "Authorization: Bearer fx_test_abc123def456" \
  -H "Idempotency-Key: $(uuidgen)" \
  -F "to=+442075550199" \
  -F "file=@invoice.pdf"
Verify: The response returns HTTP 201 with a fax_id. If to is malformed, the API returns HTTP 422 with an error code. See the error catalog for the full list of validation errors.

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Step 2: Handle country-specific dial rules

A few country-specific rules are worth knowing before you send.

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United States and Canada

US and Canada share country code 1. The number must be 11 digits total: +1 followed by a 10-digit number (area code + subscriber). Toll-free prefixes like 800, 888, and 877 work for fax, but some toll-free numbers are voice-only and will reject the fax handshake.

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United Kingdom

UK geographic numbers start with 01 or 02 in local format. Strip the leading 0 before adding +44. Mobile numbers (07) are not fax-capable. Sending to a mobile number produces a fax_failed event. See the error catalog for the specific failure reason.

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Australia

Australian geographic numbers have the format 0X XXXX XXXX locally, where X is the area code digit. Strip the leading 0 to get a 9-digit subscriber number, then prepend +61. The result is 12 digits total: +61 plus 9 digits.

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Step 3: Check destination support

Most landline numbers in North America, Europe, and Asia-Pacific accept faxes. Numbers that ring to voicemail, mobile handsets, or VoIP endpoints without fax support produce a fax_failed event. To test whether a destination accepts faxes, send a single-page document from the sandbox first. The sandbox simulates the carrier handshake and returns a realistic result.

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Verify

Send a fax to an international number using E.164 format and confirm you receive a fax.delivered event on your webhook endpoint.

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What to do next

  • Error catalog for international-specific error codes
  • Glossary for definitions of E.164, T.30, ECM, and other fax terms
  • Try sending to the sandbox magic numbers before switching to live