Why is my internet data usage high when not home?

Bravo Ret60sb and Asch,

    Both of you are correct on the overview, but lacking in explaining terms.

1. De-Googling your phone. If you have an Andriod phone and paid in full. You will need to have your phone un-locked, and then load a clean Android image on it for full control. You can search the I-net for instructions and specific actions to take. Unfortunately you also may 'brick' (render useless) the phone. I have never done it personally. And this is NOT the venue to post questions. (Note: Ret60sb calls some of the activity 'automatic spyware'. This is more a IT insider phrase for the automatic updates. You can disable a fair portion by disallowing location services to some apps. Also do not simply 'accept' cookies'. With the California privacy law in effect, most sites now give you the option to change what cookies are accepted.)
2. Wireshark is a great tool … for any IT network techs, but something of an initial handful for the novice. That said, install it and run it. Record a session and save it. Then load it again into Wireshark and just page down through the information. Only small portions are in 'Plain English', but you can also see what IP addresses the information is flowing to. Again, use the I-Net to lookup and view more information on what you are seeing and how to utilize everything Wireshark offers.  (Note: the community venues here are NOT the place to ask questions or receive information. )
3. Final Note: The forums here are not places to ask for further information. Only new IT techs who have yet to get burned out may answer. And olde phartes such as myself just don't have the patience for the 'back and forth' needed to really help people.