If you DO NOT have a Chalk Mountain Services Email Address, please make sure you have a copy of your most recent paystub in either paper or digital form. You will need to visit the nearest AT&T Retail store and bring a copy of the flyer (linked here) and your paystub.
If you DO have a Chalk Mountain Services Email Address, you can validate online by visiting https://www.att.com/shop/wireless/iru-check-for-discount.html.