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sinch-api-fax-send

Send a fax to a recipient via the Sinch Fax API using OAuth2 authentication.

6|2|Updated Dec 11, 2025
Search Tags:#pdf#api#webhook#oauth2#fax#sinch#send fax
One-click install
npx skills add https://github.com/sinch/sinch-plugins --skill sinch-api-fax-send-sinch
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: sinch-api-fax-send
Source: https://github.com/sinch/sinch-plugins/tree/main/plugins/sinch-antigravity-plugin/skills/sinch-api-fax-send
Command: npx skills add https://github.com/sinch/sinch-plugins --skill sinch-api-fax-send-sinch

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Sending faxes programmatically requires handling OAuth2 authentication, correct API endpoints, and document hosting, which is tedious to wire up manually. This Skill performs the Sinch Fax API call directly so you can send a document to any fax number with a single command. ## Core Features & Use Cases - Direct Fax Sending: POST a fax request to the Sinch Fax API v3 with a recipient number and a public document URL. - OAuth2 Authentication: Uses your Sinch project key ID and secret to obtain a Bearer token automatically. - Status Callbacks: Optionally register a callback URL to receive fax delivery status updates. - Use Case: A legal office needs to fax a signed contract PDF to a client. Provide the recipient number and the public URL of the PDF, and the fax is dispatched immediately with a returned fax ID for tracking. ## Quick Start Ask the assistant to send a fax to +14155551234 using the document at https://example.com/document.pdf via the Sinch Fax API.

Frequently Asked Questions about sinch-api-fax-send

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I send a fax using the Sinch Fax API?▼

Send a POST request to https://fax.api.sinch.com/v3/projects/{projectId}/faxes with the recipient number in the to field and a public document URL in contentUrl. Authenticate with an OAuth2 Bearer token obtained from your Sinch project key ID and secret.

What credentials are required for the Sinch Fax API?▼

The Sinch Fax API uses OAuth2 and requires a project ID, key ID, and key secret from the Sinch Customer Dashboard. These can be set as CONVERSATION_PROJECT_ID, CONVERSATION_KEY_ID, and CONVERSATION_KEY_SECRET environment variables.

Does the Sinch Fax API require the document to be hosted online?▼

Yes, the document must be available at a public HTTPS URL, such as a hosted PDF. The API fetches the file from the contentUrl you provide rather than accepting direct file uploads in the request.

How can I track fax delivery status with Sinch?▼

Include an optional callbackUrl in the fax request body to receive status callbacks at your webhook endpoint. The API also returns a fax ID on success that you can use for tracking.

Why does my Sinch fax request return a 401 error?▼

A 401 error indicates authentication failure, usually from missing or invalid key ID and key secret credentials. Verify your environment variables are set correctly and that the OAuth2 token request succeeds before sending the fax.

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