Replacing a Modkey 16 with Asterisk

I’m trying to replace a Modkey 16 system with 3 incoming lines and 5 phones in Rockford IL. I’ve got my asterisk server set up and working with 3 channels configured on my TDM400P (FXO Modules).

Everything worked fine on the test bench in Milwaukee, but when I plug in the 3 CO lines in Rockford, I can’t make or recieve calls to outside telephone numbers. When I try to make a call, I just get dead air.

I’ve got the TDM400P set for Kewlstart FXS Signalling. When I tried FXS Groundstart it gave me the ‘Invalid Argument’ error (see the O’Reilly book, chapter 4, Page 63).

I’m pretty confused at this point. Does anyone have any suggestions for what I should check next?