Updated: 1/14/24
Reference: End-to-End Encryption
If you're NOT using a "Secure" Messaging App" for your SmartPhone, then ALL of your "Chats and/or Texts" are being transmitted thru the Air "insecurely" or in "Plain Readable Text"! The only SURE WAY to secure/protect your texts, is to utilize a Secure Messaging App.
The following are the Best Secure Messaging Apps (available).
WhatsApp (iPhone & Android) -- A cross-platform mobile messaging app which allows you to exchange "Encrypted" End-to-End Encrypted (ee2e) messages without having to pay for SMS.
iMessage (Apple) - Uses End-to-End Encryption (e2ee), however, Apple's iCloud does NOT use (e2ee) and many users are NOT aware of this lack of security for all of their data in Apple's iCloud.
Signal Messenger (iPhone & Android) -- State-of-the-art end-to-end encryption (powered by the open source Signal Protocol) keeps your conversations secure. We can't read your messages or listen to your calls, and no one else can either. Privacy isn’t an optional mode — it’s just the way that Signal works. Every message, every call, every time.