I don't know your mail address or telephone number. If this message manages to reach you - can you explain your point a bit more?

If the private key would _be_ the identify, that'd be awesome. And maybe I fail to understand ChatSecure/Signal. I'd be glad to be corrected. But as far as I understand, that system ties a user to a mobile number, because 'that is as good a unique identifier as we get' and uses that instead. I think Threema does what you describe - or at least expects you to exchange keys via QR code when you physically meet?

My gripe with telephone numbers is this: I don't want to be tied to an identity I cannot control, to an identify that is public knowledge and unchangeable. I want to contact people via IM without them being able to call me.

Phone numbers are for calls (okay, texts for historical reasons).

F.x. I installed a while ago Signal on my phone and recently went to another country where I used a different SIM card (hence a different phone number) and I could still use my Signal app as usual.