I just wanted to save everyone some time. We had an issue where we could receive faxes fine but sending would fail.
Under the Line 1 Setup I changed the number from 1-xxx-xxx-xxxx to xxx-xxx-xxxx. Also I changed the fax defaults from 33600 to 14400. Now sending works reliably. It was connected to a true POTS (not an fxs but a real ilec fax line, at&t)..
