It's still federated identity. Phone numbers are a federated structure, but the federation occurs at the level of telcos and nations; you are denied the opport

It's still federated identity. Phone numbers are a federated structure, but the federation occurs at the level of telcos and nations; you are denied the opportunity of self-management. They also predate the domain name system, making them the "traditional" format, an anachronism rather than the future. I'm looking to wearables and low-power IoT devices, and for those we may need a new federated identity/discovery scheme. The DNS is practically ancient now, but has served email, web and XMPP and many other protocols besides surprisingly well for decades. I doubt it is sophisticated enough for global-scale wearables and ubiquitous sensors. We could never have built anything so sophisticated on phone numbers. Most of your remarks seem to align with the preferences of chat app developers. But actually there's no group I'd trust less, today, to determine the future trajectory of communication. Interoperability, federation and end-to-end behaviour is the open architecture of the Internet, and I believe anything that undermines that triad should be met with contempt and resistance.