I just got an email announcement from obi suggesting that the obi 200 series could be used to connect to voip-based security systems -but, as is typical, no explanation of what that means. I have been using two voip alarm systems--- both using proprietary devices from each company to link to my router (bypassing the obi 100 devices I have). Does anyone know how the the obi 200 devices work in this context?--- do they allow avoiding purchasing a separate internet bridging device?
No, that's not what the announcement said or meant.
You can use an OBi 20x with Google Voice, to replace a POTS line connected to an alarm panel. From the alarm panel's perspective, it just looks like a POTS line. The alarm panel is still using the standard Ademco DTMF protocol to communicate with the monitoring center over a dial-up PSTN connection.
This solution does not create nor use and direct interaction between the alarm panel and the alarm monitoring service via VoIP.