It is one thing to have Alarm Data transmitted from remote sites to the control center via the Internet. But, it is ENTIRELY another thing to allow Control Commands to be sent from the control center to the remote sites via the Internet. You are just BEGGING for trouble.
The solution ??? Simple, you install a terminal server and a dial-back modem at each remote site and at the control center.
Using this method:
1. The control center could receive alarm data via the Internet, but would have to dial the remote site via the PSTN to the dial-back modem.
2. The dial-back modem would then drop the control center's call and dial back to the control center's pre-programmed telephone number [in the dial-back modem].
3. Once the remote connection is established, the control center has to put in a username and password.
4. Once the dial-back modem authenticates, the remote site is controlled via SNMP commannds over an RS-232 interface through the terminal server.
Cost for the equipment at each site ??? About a thousand bucks. Monthly recurring cost for PSTN ??? About 20 bucks ...
Sadly, they’ll never listen to you and do that because it makes too much sense and it’s too cost effactive (not enough money for kickbacks). It’s insanity.