But, in that case they'll have local context. Many issues have been dealt with by mobile vendors, and they do have a large namespace. The use of smart cards in Europe address many concerns. For instance my smart card offers services. And that perhaps the end points are nothing but telephone numbers.
Service can be mobile.
But I can use Voice Dialing to find a place for you. This is a service that I have from the Telecom. Ten years from now, the unrecorder life won't be worth living. We will record entire lives on video and exchange video. Humpty Dumpty gets along just fine without names.