I'm trying to get 3CX to work with the SPA3000 for a analog fax machine. I the past I used this Linksys SPA3000 with the Askozia PBX software to send faxes from an analog fax. this worked great. Now I tried this with 3CX and it just does not work anymore. If I make a call with an analog telephone true the SPA3000 adapter , it works. If I make a call to an external fax nr then I can only hear the first handshake beeps from the external fax and then the line just disconnects. I have no clue where the problem is. But I do not believe the problem is in my SPA3000 setup since I can make normal calls. And it worked with Askozia PBX.