Wanted: Point to point Internet Monitoring System for alarm conditions at client site

I am looking for a stand-alone Internet alarm monitoring system with the following characteristics:

1. Hardware boxes at the remote client site and at the alarm monitoring location that will report loss of communications, client alarm conditions, and other malfunctions as contact closures (at the monitoring site). The monitoring center should periodically check for heartbeat signals from the client site and sound an alarm (close a relay) should the heartbeat signal disappear.

1. Ability to monitor the position of and throw relays at the client site from the monitoring location.

2. The whole thing runs on IP (Internet Protocol) and may be plugged into a device like a cable modem or DSL router at the clients location, just like a computer.

1. Automatic backup (dialup) over POTS lines (optional) would be desirable.

Can anyone point me in the direction a manufactuer that makes something like this?