Sending fax using extensions g.711

[Andriy]

Hi everyone,

Does anyone know if i can send FAXes using normal extension (not Fax extension or Fax server)? I am trying VentaFax and it connects to the extension without problem, but can not send fax with this error:

"Modem detected BUSY signals while playing sound"

The reason why I am asking is
1) I am using PBX express and I want to connect fax soft-phone remotely. I can connect to normal extension by allowing connections outside local LAN in options, but when trying to connect to 88 FAX extension - I am getting this error:
"Block WAN requests is ON. "

2) I have 3 locations, and I would like to use different extensions and DIDs for each of them if possible.

3) My voip provider does not support t38 yet

Thank you.

 

[eddv123]

Hi Andriy,

Be aware inbound FAX works fine with 3CX out of the box but if you want outbound you will need a VoIP gateway (FXS to be precise of).

Also be aware that the FAX server with 3CX only works locally or via a locally routed subnet (like a VPN).

T.38 is the preferred method over G.711 as G.711 is bandwidth intensive but your provider must support T.38 FAX for it to work.

 

[Andriy]

Well,

1) I would prefer to use softphone (like Ventafax) instead of connecting a real Fax machine via FXS - is it possible? I was able to connect to to normal extension from VentaFax and to 88 Fax extension but I still get this error: "Modem detected BUSY signals while playing sound"

2) I know t38 is better, but My voip provider does not support t38 so i have to stick to g711 for now. I have one more provider, that seems to support t38 but it has same problem as described above.

 

[eddv123]

Well this string does suggest that this will work locally: https://www.3cx.com/community/threads/fax-client-out-the-office.48796/

You said in your first post "I am using PBX express and I want to connect fax soft-phone remotely."

If you are remote to the system (and not running across a VPN) it won't work. This is why you are getting "Block WAN requests is ON. " as the FAX server will only serve local, or locally routed clients.

 

[Andriy]

Thank you for reply...
I was getting Block WAN requests is ON but then i tried to connect via SBC - and it worked - at least i was able to register,

But now when I am trying to send a fax - i can hear FAX sounds, but later VentaFax gives this error:
"Modem detected BUSY signals while playing sound"

Thank you