What can be done to ensure dial tone on a VoIP system is maintained over general power failures?

a. Power over Ethernet Five 9 service (99.999% reliability)

b. Better backup batteries for IP Phone

c. Use PSTN with VoIP phones

b. Better backup batteries for IP Phone

Explanation:

Five9 is an all-inclusive cloud-based contact center for outbound, blended, outbound as well as omnichannel centers from all over the world. And it is fueled by practical AI. It leverages the agents in providing the best customer experience through email, phone, mobile, chat, social and much more. And VOIP is the combination of PSTN and voice over IP. However, the VOIP system will not work with the internet, and hence without Power. And power can be ensured through only the better backup batteries for the IP phones. And hence, b is the correct option.