Normally Calls or SMS via SIM card always insecure.

But Calls and SMS via SIM is always preferred way to contact each other but it's completely insecure and SIM Companies can collect and store this information however they want.

But we can add encryption in clients.

As for SMS we can just use Signal RatChat Encryption Protocol to send encrypted SMS or MMS.

But what about Calls?
In Calls there is no way to add public keys to encrypt content before negotiations starts

Then how about "Convert Data to Sound and Sound to Data"

When UserA start Calls for the First time,
It will send the Public Key Data Converted into Sound to UserB then UserB will accept that Public Key Data Converted Sound into Data.

Then UserB will send Public Key Data Converted into Sound to UserA then UserA will accept that Public Key Data Converted Sound into Data.

After negotiations of Public Key Data finally Done!

Immediately any sound which getting from microphone starts to get encrypted by that public key then converted into Sound then send it to other client it will get converted into data then it will get decrypted by the user to hear the actual voice of other user

What do you guys think?
Share you opinions

Its been done and is used. The issue is voice compression codec, call quality and if you are sending it as a cellular voice signal each person needs the setup. The ones I have seen and been privy to are hardware connecting to phone thru usb phone audio jack or bt. I do not know of any that are on the public market. Of course you can just use signal for messaging and encrypted voip over data connection.

    Nobody
    Yeah.

    I can use Signal but i am thinking about peoples who don't even know there information is always in someone else hand.

    Even at this moment internet is not an option for Lot's of people (even though they have android phone's)