There's not much one company can do about the standards. [1] They can only control their own output.

Apple asserts that Facetime and Facetime Audio are end-to-end encrypted. And Google claims Hangouts are encrypted as well.

I don't know whether there are caveats (or how many) to either of those claims. But that's about as much as one could hope for in the current climate. [2]

[1] Particularly upstart computer companies dealing with the telecom oligopoly. Long cozy with governments and law-enforcement, if not an explicit part of government.

[2] It's a serious bummer that FaceTime never developed into the open standard they claimed at introduction. I've been curious about where that fell apart. (Competitor disinterest, patent liability, carrier terms, etc)