I hear you, and I don't run a massive fax gateway or anything like that. Doing somewhere around just under dozen faxes a day or so to generally a different fax numbers each day so its mainly just seeing a variety of remote fax machines and input. Generally we try 3-4 times per fax, and fall back to a PSTN fax machine that always succeeds and just about on the first try every time. With FS/spandsp we get "Timed out waiting for the first message" or "Invalid response after sending a page" or "The call dropped prematurely" probably at least 15% of the time on the first try (t38 req on and ecm on). With successive tries though (t38 req off and ecm off) we generally get it to go through. We have also tried phaxio which I believe uses spandsp also. Frequently on numbers that we have an issue with they will have an issue with also, however after a few tries (sometimes upwards of 5 minutes later) they do seem to get them to go through. Part of the reason I think multiple carriers may just help the situation (as I am not sure what they change other than that to get it to eventually work). I have yet to find a number phaxio hasn't eventually succeed on however. Also obviously didn't mean to offend, the 95% was just to give people an idea that while it can be good it doesn't quite seem to be a replacement for a PSTN line yet. I love FS / spandsp and it really is excellent. ~Mitch