We've had a few instances where a remote site will be come unreachable, and
can no longer dial in to our central site. A known working router placed at
the remote site is able to dial in just fine. Taking the suspect router to
another known working ISDN shows that it still cannot dial out. It seems like
the BRI port is getting damaged in some way. Is this possible and what questions
should I ask my local phone company to troubleshoot this? It's happened more
than once at two particular locations, which are rather remote and are probably
using repeaters to boost the signal.