Yes, Cox telephone uses a different signal than Internet as well as TV. All three services use the same cable albeit on different frequencies.
Yes, Cox telephone modems (eMTA) have internal and replaceable battery back-up capabilities. As far as I know, Internet modems do not have this capability.
As long as you have a serviceable battery inside your Cox eMTA, you'll have telephone service until the battery depletes. If you have an all-in-one device (eMTA & modem), the battery will only power the eMTA...not the modem. Therefore, if your only power source during an outage is the battery inside your eMTA, you will not have Internet service.
To use telephone service during a power outage, you'll need to connect a corded telephone...that does not require power...directly to the telephone jack on the eMTA.
If you have another phone service and your telephone and modem are connected to an UPS, you should have service.
The new Cox telephone service with an aMTA is called Cox Voice. Cox Voice is an Internet service...VOIP...a packet-switched voice connection. It's the same technology as OOMA, Obi and Google.
So lets say you have two next door neighbors who both have Cox internet. One neighbor also has Cox Voice with a backup battery installed in their phone modem and a corded phone. The other neighbor has OOMA with their cable modem, router, and OOMA unit plugged into a UPS backup power supply, and a corded phone. The neighbor with OOMA would have their phones working for the same length of time as the neighbor with Cox Voice?
Connect OOMA to the modem and you may get 4-8 hours on the UPS.
