You need to route the DID to the fax server. 3CX doesn't do fax detection, it has to be specific DIDs. Also, if even that doesn't work, make sure your DIDs are entered in the correct format required by your provider.I have been trying to get in bound faxes to work, but calls keep getting directed to voicemail. Sip trunks require a default route and the fax server or service is not avaialble.
I have tried all of the US providers...
Documo... why reinvent the wheelSending a fax from email is not something you will find from 3cx, however I a working on a system that will do that very thing using Telnyx API, DM me if interested
Take a look at Documo. It has an API, uses Telnyx in the backend, and is very cheap & modern. Instead of doing everything on your own.why reinvent the wheel? To manage from our booking system, as a manager of a RV Resort we have to sometimes send faxs from our system, as for receiving the fax 3cx handles that for us


Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.