I’m thinking of how to keep an alert going out to the call center in the event power is out. I guess that would mean a battery backup for modem, router, and Wyze base station, correct?
Does the base station already have onboard battery backup?
Any other ideas on how to harden the system to maintain operation?
By base I assume you mean the HMS hub, and yes it has a battery. The answer to your other questions is you need backup power for all the hardware needed for internet connectivity; modem, router, etc.
This is the backup power I use for my internet, WiFi, and Wyze Cams the same setup could power a Wyze HMS
Battery Backed-Up 14 V3 cams and Internet Communications