RedHenry
Threat analysis starts with a simple question: Who are you trying to defend against?
If you are concerned about the interception of your phone calls or text messages then use Signal. There is no realistic way for you to defend against a targeted attack from an entity that is manipulating cell towers or the phone/SMS infrastructure.
Run all of your data through a reputable VPN and use Signal for your phone and messaging needs to the largest extent possible.
There are other mitigations that can be done but they require skill, resources, and/or ease of use limitations that likely render them impractical for your situation.
Use GOS, use Mullvad, only communicate via Signal or SimpleX from a secured profile dedicated solely to that use and protected by a strong password/phrase, and the number of threat actors who may be able to intercept and/or manipulate your communications via technical means basically begins and ends with the NSA when the agency is actively invested in targeting you.