Re: AT&T also added no carrying unused bytes to a new month
It is, but only on the 200MB plan.
said by ATT :
On the 200MB Data Connect Plan, once you exceed your 200MB allowance, you will be automatically charged $10 for an additional 100MB.
However, if you have the 5GB plan (and practically anybody halfway intelligent will), it's the prices listed above, which translates to $49.15 for the same 100MB.