Fax to desktop in Trixbox 2.8 works, but in an unexpected way...

Patrick, Changing extensions_additional.conf is not recommended. The file is overwritten every time a change is made in the configuration.

You may be able to place these changes in the extensions_override.

First, thanks to Skyking for pointing out that changes to the files managed by the AMP functionality (most core files) are at best, ill-advised, and suggesting using the override files. I had used that override functionality in the past with success, but never to secure changes to every individual extension. The overhead of making sure that changes propagated from the edited file (extensions_additional.conf) to the appropriate parts of the override file turned out to be too onerous for my client. So, we settled for a little shell script that changes the syntax after every inbound route or extension edit. As it turned out, that was not the core problem anyway.

Second, the core problem turned out to be that as installed in the default way, the NVFaxdetect mechanism simply did not work on the client's PRI. With considerable help from Fonality, a custom context was generated for the from-trunk/from-pstn contexts to include that forced detection. We had to create a local variable for all the individual extensions, but that was a small price to pay to get the desired functionality of a direct fax to the desktop working. You might note that I am careful to say the client's PRI, although, I am fairly confident (based on setting up some equipment to emulate PRI's that I had acquired) that it wouldn't work on any PRI.