@Laberpferd
100%
However, I have registered #Threema without having to provide my cell number, it is optional.
Of course, I have to use mobile internet, when I am on the move, but I can use a VPN.
So, where do you see the risk with #threema?
And, besides, mobile phone calls and SMS seem a lot lesse secure to me.
I once had a discussion with a cyber security pro what means of communication is really safe: meet at a remote location in person, that's about it.
Point being: