Yeah, end to end encryption works nice if both people are using it. I believe Whatsapp now has end to end encryption on text and voice but since it's owned by Facebook???. Banks use their own messaging center on the web site itself to keep things secure.
phone conversations are much better protected legally
You need a warrant to tap a landline but I'm not sure how mobile works. The new SCOTUS rulling requires a warrant for phone location but I don't know about the cell call itself. The NSA sucks down cell calls without a warrant.
Any service offering end-to-end encryption would have to be insane to provide any workaround for it. They've got their business to protect, and that includes businesses owned by Facebook.
I believe you need a warrant to do the equivalent of tapping any phone call, but I could be wrong. It would certainly be very easy to intercept calls from both wireless phones (as in for landlines where there's a base unit and handsets) and mobile phones if you know what you're doing, but it's still probably not legal.
The NSA surveillance, based on all reports, was related to location data, not call content (but, of course, one knows that they'll be monitoring call content that they believe needs to be monitored, but likely with warrants within the USA).
Again, we're back to an, "it's the nature of the beast" thing. Even if the NSA and other entities are forbidden from doing this, and were honoring that, the nature of the technology is such that those who wish to behave illegally have the ability to do so with ease. And that's even in regard to listening in to calls. Of course, wiretapping is very easy, too, but the legal penalties for doing so are very steep. That still won't prevent those that really, really want to surveil from doing it.
I have said, again and again, that people need to understand the actual risks posed by any technology they use. E-mail and mobile phones cannot be considered to be secure means of communication, and that's been true of both since their introductions. To believe otherwise is to ignore a vast amount of history at this point and one must operate under the understanding of what is.