T&T myWireless Mobile allows you to manage your AT&T wireless account from your iPhone.

With this application (portrait view only), youll be able to manage account functions including:

-Viewing and paying your bill
-Viewing voice minutes and data usage
-Adding or removing features

Note:
You must have an active AT&T Mobility account that is registered for online account management to use this application. If youre not already registered, visit http://www.att.com/mywireless to register and then download the AT&T myWireless Mobile application.
AT&T myWireless Mobile does not support Premier business accounts or GoPhone/prepaid accounts.

Download Here