A phone number is less of a problem as you have portability. Or you can have it. In the UK for example, regulation means that you can automatically transfer your number between providers at no cost. It's a painless process.

That's going to be a lot more difficult when your email address is tied to a certain domain, like gmail. I think there has to be a different kind of solution there, that is more accessible to the layman than setting up your own domain and dealing with MX records and stuff.