The idea of moving security and emergency over to the Internet really scares me.
I still think it would make more sense to have this functionality in the ONT where its not reliant on the quality of the Internet or routers.
Have a two-port Openreach owned device (ONT or otherwise) on ALL broadband connections, with the ISP over one port and telephone over the other with QoS to ensure the broadband traffic never trips up the telephone service. It seems a safety hazard that Openreach don't want to take on this responsibly, instead passing it all onto the customer and/or ISP.
This is going to be an absolutely nightmare for vulnerable customers.