If the AT&T phone service is personal, then the settlement check is not reportable income to you. This would be the case in most situations. So for tax purposes you would not show it on your return.
If you deducted your AT&T as a business expense on your return for the period of time the lawsuit is for, then the settlement would have to be reported.
The settlement resolves lawsuits concerning AT&T Mobility charging Internet Taxes for internet access through certain services.