I decided to share this solution for those who might be interested:
When you use Nagios to monitor a network, Nagios still needs a part of that network to tell you that something is wrong! If your Internet connection goes down, you will never know until the connection comes back up.
So I built a plugin that will use a voice modem to CALL ME when the T1 line goes down. And it uses Festival so it can actually speak.
The script is offered as-is, with no warranty. There is no install script. Some lines will have to be changed to match your system.
See the link for more details.