Preventative maitenance for diag modems


I am trying to find a tool to monitor the availability of our diag modems.
There have been instances where we were in need of gaining console via the
diag number, only to find that it is RNA/oper rec/etc...

Can anyone point me toward a tool for this? I heard a rumor on #nanog that
Verio has a very nice tool for this.

Thanks for your assistance!