You don't have to actually enter your email address, you just have to prove that you know it - and telephones have the full alphanumeric set of characters on the keypad. Use a * or # for special characters, and something like "[email protected]" could be entered as "72835#547446#674".

Edit: I guess that may not be sufficient to identify you, but it could verify that you are the account holder for other services.

My cell phone (Pantech 5000) has a qwerty keypad. It doesn't have the old rotary phone style letter-number association. I know many people whose phones don't have this.

Ok, but you can't do dtmf with querty, so its use in a call center is somewhat less important.

With standard numbers, you could use any touch tone phone.

What I mean is the map of 2 to a,b,c is fading fast. I can't figure out how to dial 1-800-CALL-ATT by looking at my phone, much less my email address.

Some people have 20+ character long email.

You really think they are going to be happy about sitting around typing that in on their phone hoping they don't make a mistake ?

Voice to text works fine for limited input. So if all you needed was the letters of the alphabet (rather than words) it works pretty well.