Are you still having the problems? If possible check with the DT provider to see what switch they are fed from (dms/5ess/ewsd)and if they are fed via to a slc "slick". We have had problems on other voicemails when the lines are to "clean", ie not enough sidetone, no echo; but they used dialogic or rhetorex boards and you could adjust the dsps so that you could counter this, I don't think the vmi cards have the same capabilities.