[Freeswitch-users] T.30 Fax and Echo cancellation

Hi I know that all echo cancelers are supposed to shut down when they hear the CNG or CED fax tone. Is this always a good thing ? I know that T.30 is supposed to be half duplex, so echo should not be there but in my session recordings, I have seen both sides trying to send at the same time (is that a sign of some other bad thing?) What if my T.30 fax is failing due to echo ? Check out this article http://connectedplanetonline.com/mag/telecom_oil_water_fax/ Thanks, Anita.