Actually Textfree Unlimited now does use a real phone number. When you register you pick the number from a list for your area code. You will be using a different phone number for texting and if people call that number they will hear a message telling them it is not for voice. Currently Textfree does not have MMS, but they are getting it soon.
I have told all my contacts what the number is for texting and I will soon be canceling my AT&T text plan, saving me money.
Oh, Textfree Unlimited does have a small ad at the bottom of the screen. If you don't want ads, you have to pay $6 per year to remove them. The ads don't bother me, so all my texting is totally free!
I do know that, but I'd rather just use my own number with a generic ring tone. I'm a minimalist and like to keep things simple.