It's even easier to just have preshared phrases that have unique meaning. "Your rental car payment is due." "OK, I will pay it on Wednesday at 10am. Stop nag

It's even easier to just have preshared phrases that have unique meaning. "Your rental car payment is due." "OK, I will pay it on Wednesday at 10am. Stop nagging me." I would imagine that if enough people knew everything had lawful intercept, then they would just obfuscate their communications.