I've recently noticed some troubles sending outbound faxes. It had been working just fine (I've been a long time WxC customer - now Vodafone).


I'm using a Grandstream HT701 ATA which is connected to the asterisk machine. The HT701 has t.38 enabled and as does the machine has t.38 enabled for chan_sip.


This combination used to work great, until recently. Now suddenly I can't fax out (although I can't say when the last time was that I faxed, it is very rare) but for certain things its a requirement (don't ask).


When dialling for a fax, I hear the remote end ringing, pick up then hear the fax tones. Eventually after about 10-30 seconds I hear the remote end hang up.


Where to start troubleshooting this?