Gmail maybe, making an account at mail.com was dead easy. On the flip side, you have to keep pointing out "mail, without a g at the beginning," so who knows if that's worth it.
Gmail actually banks on the idea that most people just fill out whatever fields they are presented. The phone number is not actually required to register an account.
If you keep using the account at one point you'll be required to add your phone number or you won't be able to login.