Fax Server not working

[gehri]

Hi,
i'm facing since 3 weeks with the ingoing fax server.
When i send a fax to the fax DID (in our case *011) there's no fax tone and the negotiation phase remains till a the user hangs up because of the busy tone.
See attached logs (3CX IVR and Activity Log).
What can i do?

 

[JasonNadeau]

what version of 3cx are you using ? I'm having fax issues with the 15.5 beta but haven't yet confirmed it's a 3cx issue ...

 

[gehri]

Using 15.0.62928.5.
Don't want to install over the beta, because it's a production site.
Any idea?

 

[StefanW]

there is no fax tone as the fax server you hare having is "digitial" or in tech terms T.38. So I assume that the provider you use can not process t.38. You can have a classic fax tone in 15.5 beta as the fax server contains the option to be in audio... give it a try...

 

[gehri]

Hi StefanW,

thanks for the information.
A technician from our SIP Trunk provider (Sunrise Switzerland) told me T.38 is already on as the primary fax protocol.
So i don't really know what could be the issue.