My suggestion to anyone seriously worried about security – Consider the Internet access on your device no more secure than open WiFi at a coffee shop, and assume Calls/SMS are no more secure than a public conversation.
In short, use data/internet based over the top applications with encryption that you trust, obviously also trusting your endpoint/device too.
However remember that even that does nothing if your worried of location/device tracking.
There are legitimate reasons for doing this (one great example is to never get caught unwittingly in a geofence search warrant), but mostly it's not worth the trouble. And that's why no one does it.
All this to say that you should treat all the info you give to telcos as leaked from that time, and act accordingly. The only way to seriously avoid leaks is to give them nothing to leak.
Use communication software you trust (Signal?) over VPN on IP networks (cell/wifi/wired).