I have a DSL-only plan with AT&T. It works fine, but every time I call for support, they ask me for "the phone number on my account", and I have to re-explain ten times that I have only DSL, and not phone or TV service. Often I am told that it is impossible.
Whether you buy phone from them or not, you still have a phone number associated with your account (cell phone etc), just a way to look up your record.
At least for my naked AT&T DSL, there's a 'fake' phone number (0-xxx-xxx-xxxx) associated with the account. Usually, the automated prompt won't recognise that number, but human representatives are fine with it.
