Question 1

How does an agent send a fax?

Accepted Answer

POST a multipart request to https://sendfax.sh/api/v1/faxes with `document` (a PDF) and `to` (an E.164 fax number). You'll get HTTP 402 with payment requirements; pay with any x402- or MPP-capable client and retry with the payment header. The response is { id, statusUrl }. Poll GET https://sendfax.sh/api/v1/faxes/{id} until the status is delivered or failed.

Question 2

How much does it cost?

Accepted Answer

$0.05 per page, settled in USDC on the agent rails (x402/MPP) with no minimum. The human Stripe checkout has a $0.50 minimum charge.

Question 3

Do I need an account or API key?

Accepted Answer

No. There are no accounts and no API keys anywhere. Payment is the credential: the per-request x402 or MPP payment authorizes the send.

Question 4

Do you store the fax?

Accepted Answer

No. This is a real-time fax service. The PDF is streamed to Telnyx and deleted after sending; we never store the document, and the destination number is redacted to its last 4 digits at terminal state. We keep only process metadata (ids, statuses, page counts, timestamps).