AT&T has a large customer base, so a threat to them is nothing. Especially from a 1 to 5 line plan. Start telling them you are leaving and taking your 100 lines from your business with you and they will start listening.
They are in the business to make money, not give it away. Yes, we all know that they have minutes and airtime to burn, but why give it away when you can make a penny or two.
As stated before, I have never, in my 13 or so years with AT&T/Cingular have received anything from them for free....except for the occasional cheap, free phones that have to be subsidized over two years........Hey, wait a minute!!!