All calls to the Phaxio API should be made to For most calls you will need to pass in your API key and API secret as parameters. You can find your API credentials on the “API Settings” page. In Phaxio, there are two types of credentials: live and test.

Early TLS sunset notice

The Phaxio API endpoint currently supports TLS versions 1.0, 1.1, and 1.2. However, after January 15, 2020, support for early TLS versions will be removed and only TLS version 1.2 will be supported. You can confirm that your client supports TLS v1.2 by temporarily testing with This is a temporary test endpoint and will be removed after January 15, 2020.

If you make an API call with a live key, your balance will decrease if you perform operations that cost money (e.g. you send a fax). However, if you make calls with test keys, the Phaxio system will simulate faxes being sent or received and your balance will not be affected.

All Phaxio API responses are formatted in JSON. Need an XML response? Too bad. JSON is awesome! Click here to learn more about it.

Parameters that look like this are optional, whereas all other parameters are required.