What are the tools for secure voice communication?

Question

Encryption

Good afternoon.
I am looking for ways to communicate safely by voice using technical means, such as a telephone.
The idea is simple. The voice must not be heard by third parties.
You can say - use a cellular connection / skype / viber - everything is fine there. But in the Russian Federation, having the right contacts, you can listen to these channels.
As an option, I consider:
1. Telephony server abroad + SIP client on a mobile phone.
2. Skype for Business (Lync Online), but I'm not sure about the stability of his wiretapping.
What else do you recommend?
Thank you.

Answer 1

tox

Answer 2

Let's consider the situation hypothetically, if they want to listen to you, then it is easier for any special services to plant a bug in the old fashioned way than to find out what it is you use to make calls and how to hack it. IMHO)

Answer 3

Encryption must be two-way and you must be sure that no one is listening on the other end of the "wire". Try more private cart chats

Answer 4

secushare.org/comparison