Been running phoco flawlessly for 2 yrs with 0 echo. I have a "push down" cut off button where my power window buttons are located in the door. Press the button down which closes the mic circuit and you can speak. Normal state leaves the circuit open that mutes any sound from the mic being regenerated back from hearing itself from the car speakers. This way the caller does not hear themselves, nor do I hear echo from the mics volume as it has been disabled.

..think walkie talkie, but one way. So the settings I am talking about do effect the echo as the mic can not hear nor the software have to decide what to cancel as I do it manually. Works great. cost 5 bucks for the button.

Watching your advancement on a phone solution, been playing with the trial, so far I like