I was actually thinking about this before I posted and discounted email. It has high interoperability but you cannot move your email address to a different prov

I was actually thinking about this before I posted and discounted email. It has high interoperability but you cannot move your email address to a different provider if you didn't opt to use a domain you owned. This is obvious when you say it but I can port my phone number between phone companies whereas I cannot move my Gmail address to a different email provider.