Programmable Fax API

Reliably transmit documents with Fax over Private IP

Send and receive fax via API for unmatched flexibility, security and reliability.
Questions on setup? Talk to our fax experts
Build on a RESTful API with unmatched developer experience and support.
  • Intuitive, Robust API
    Write just a few lines of code to send and manage fax programmatically.
  • Secure your communications
    Send and receive secure fax wherever you are on our global private IP network.
  • Eliminate errors
    Our advanced error correction features ensure your faxes get delivered with confidence.

More Ways to Fax

Programmable Fax API

Send, receive, and manage faxes without a fax machine. Build with a set of simple HTTP endpoints using our Programmable Fax API.

Traditional Fax over SIP

Connect your fax machine to the Telnyx network to transmit and receive faxes via SIP Trunks, with zero per-page charges.


Fax Features for Total Control


Send, receive and manage faxes in a few lines of code with our Programmable Fax API.

Enhanced Security

Safeguard your data with encryption of signaling and media, and transmission over our private network.

Private Network

Strengthen your faxing with a purpose-built, private IP network, and certified fax-ready SIP trunks.

24/7 Support

Our in-house fax-experts are available around the clock, for all of our customers, with no minimum spend commitments.

Quality Routing

Access premium outbound routing with direct connections to Tier-1 faxing partners across our network.

Protocol Choice

Deliver faxes via T.38 or G.711 pass-through, and control T.38 re-INVITE initiator for deep configurability.

Elastic Scalability

Scale on-demand to handle as many inbound and outbound faxes as you need, exactly when you need them.

High Reliability

Enjoy a guaranteed 99.999% uptime SLA thanks to our resilient multi-cloud network architecture.

Real-time Faxing that's HIPAA-Compliance Ready

  • Encrypted Fax Signaling and Media
    Enable encryption on signaling with TLS and on media with SRTP or ZRTP.
  • Secure Private Network
    Eliminate the risks of the public internet with our private IP network.
  • Real-Time Transmission
    SIP Trunks provide reliable, real-time transmission, so no data is stored at any point.
  • Automatic Error Correction
    T.38 error correction guarantees accurate delivery of information, with page-by-page confirmation.

Ready to get started?

Frequently Asked Questions

Yes - you can send, receive and manage faxes over your SIP trunks with Telnyx. This allows you to reliably send, receive and manage secure documents without the need for an antiquated fax machine. What’s more - our Programmable Fax API allows you to send and manage faxes programmatically.
Fax over IP (FoIP) is a term used to describe sending faxes using a voice-over IP (VoIP) network. FoIP uses a protocol like T.38 or G.711 to encode the file into a format suitable for sending over SIP trunks.
Fax is still a popular choice in applications where there are legal and regulatory considerations, such as transferring documents that require hard-copy signatures, and protected health information (PHI). It’s also popular as a backup communications method in case of internet connectivity issues.
You can send and receive fax programmatically in just a few lines of code using the Telnyx Programmable Fax API. Learn how to get started by checking our developer docs.

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