Ok, after a couple of issues with faxing over VFX, I thought I'd kick this off to see what the general experience is like out there with faxing over VFX. Also some good technical discussion on T.38 & G711 codecs etc would be great too.
I've had a couple of customers that I've had to revert back to a land-line for faxing, as faxing just turned out to be very unreliable. These were on below average ADSL lines, and maybe that is the issue. Possibly with ongoing troubleshooting, this may have been resolvable, but when the customer is loosing business due to fax issues, there is not much time to troubleshoot.
Anyway, here's my observations:
- outgoing faxes, these seemed to have a lot less issues
- incoming faxes, this was very unreliable. Lots of multiple faxes, missing lines etc.
- voice calls on other VFX line often cut off with incoming fax
- codecs where hit and miss. sometimes G711u, other times T.38
So a couple of questions:
- what factors are at work here?
- are some fax machines better than others? Which ones?
- why sometimes T.38, other times G711u?
- can you lock codec to T.38?
- is T.38 suppose to make faxing work reliably?
- how does T.38 work (technically) over WxC (or other VoIP) networks?