Ok, I've brought this up with 3com tech support, and they have not been able to answer my questions... I run approximately 8-10% Lost-Carrier Rates on my Quad Modem based chassis. On my DSP based chassis, that number is 15-17%. I can attribute 1 in 10 calls dropping to flakey phone lines, poor client modems etc, but beyond that, I have to question what is going on. I have tested to eliminate T1's from the equation by switching the 2 spans that plugged into the Quad-Chassis with the 2 from the DSP-Chassis, and the results are exactly the same (24 hour test period in both cases) Now I've got 7 dsp cards in service (2 chassis split 5/2) and both chassis show the 15+% loss. Any suggestions as to why these dsp modems are more prone to dropping connections? DSP Code 2.0.81 ARC Code 4.1.59-6 NMC 6.2.17 Thanks Paul