Using more secure messaging services
In most countries, it is safe to assume that telecoms are recording all SMS message traffic. Install a secure messanger app and make it the default SMS messenger.
Signal is not as strong on privacy as it is on security. It collects some metadata, and relies on central servers to manage message flow and hold the metadata it does collect.
Session is a fork of Signal. No geolocation data, device data, or metadata is collected. The Session network is decentralized, with no single point of failure, and no main server for bad guys to hack. Session moves messages using an onion routing system.
Note: Signal no longer accepts SMS messages.