This article from The Intercept explains how to prevent the NSA and their pals from transcribing your phone conversations.
In simple terms, install Signal on your iPhone (both voice and text) and for Android, RedPhone for voice and TextSecure for text and encourage those with whom you communicate to do the same.
It is a very secure, free app, and calls and text are free globally to other installed users. All of your contacts who have one or the other installed will show in the app.
You may think that what you do is of no interest to the NSA and their partners, but their activities are not really about chasing so-called terrorists. It’s about profiling everyone on the planet, and it may not matter today, but tomorrow? So, I encourage you to install and use it.