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

[invalid@xxxxxxxxxxxx (Beachcomber)]

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.

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

3.   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.

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

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