The ugly issue of faxing has rared it's ugly head again but this time I think it is actually the fax that is at fault and not the VoIP set up.

Have a Brother MFC6490cw set up with a Cisco SPA112 that is registering to a 2Talk fax line. Faxes can be sent to the fax with no issue. It works just like you would expect a fax to work on a POTS circuit. The issue comes with trying to send. The fax keeps showing 'comm.error' which apparently just means the line is not connected.

I have tried the config from the SPA112 on our work machine which is a big Canon something or rather. I can send and receive no problem which makes me think the config is good. I always use the NZ tone plan that sbiddle has set out for us on his blog and then just made the needed adjustments for faxing to work. I don't really understand how it all works though and if sending is any different to receiving.

Has anyone encountered particular issues with faxing on Brother equipment through VoIP? It has this 'compatibility' thing that can be set to 'Basic for VoIP'. I have tried all the different compatibility modes but nothing works for sending faxes yet as I say, receiving works fine.

Any light that could be shed would be excellent.

Cheers,
Sam