We are having this issue with our t1 where the router will go down and show an AIS error. THe last time a reboot fixed the issue. I think it maybe a bad WIC. I have matched the line settings on both ends, checked clock source, checked all cables, looped every interface every which way, Had telco test their end, swapped routers(same wics). I am lost. I opened a tac case also. Is is possible the loss of frames error or the ais error needs to be cleared somehow. I will attempt to reload the other router and see if that helps. Any ideas!!
I have this problem too.