Thoughts on mobile routers and ip phones

So, I have this crazy idea. Hear me out.

I know that there are routers that'll work with like a dongle connected to their backs, which means if you're some place that doesn't have like a fiber optic network, but you do get signal, you can basically setup a mobile office in minutes using a router, a compatible IP phone, and a decent system

My mum spends time in such a place and I did setup cams and what not just to make sure she is safe, but something like this would help in a much better way,mainly because I would be able to connect each cam, each device(fire alarms, CO detectors,etc.) and everything else to this one point (which hasn't happened so far). Plus, she'll get an actual landline sort of a connection using the IP phone.

I don't know if I am getting the idea across. But, I want her house to be completely self-reliant and connected even though she choses to live in that house in the woods. So, how should I implement this idea. Any help would be much appreciated