Email-style user@host.domain addressing is also used in SIP. At one point in time you could reach me on email, XMPP, and SIP all using the same identifier. We

Email-style user@host.domain addressing is also used in SIP. At one point in time you could reach me on email, XMPP, and SIP all using the same identifier. We dropped XMPP about a decade ago when all the major service providers stopped federating with it, but if you know my work email address you can also call my desk phone using the same identifier.