Send faxes to any country

E.164 formatting, country-specific dial rules, and destination support

Outcome

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

Prerequisites

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

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.

Country	Country code	Local number	E.164 result
United States	1	[phone]	[phone]
Canada	1	[phone]	[phone]
United Kingdom	44	020 7555 0199	[phone]
Australia	61	[phone]	[phone]

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 [phone] with the country code.

curl -X POST https://api.mintfax.com/v1/faxes \
  -H "Authorization: Bearer mfx_test_abc123def456" \
  -H "Idempotency-Key: $(uuidgen)" \
  -F "to=[phone]" \
  -F "file=@invoice.pdf"

Verify: The response returns HTTP 201 with an 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.

Step 2: Handle country-specific dial rules

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

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.

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.

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.

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.

Verify

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

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