Apparently AT&T and Google are splitting up. On the support page “Accepted payment methods on Google Play”, Big G announced that soon AT&T billing is no longer supported as a means of payment (via android police†
Beginning this month, new subscribers and users who do not currently use carrier billing for Play Store purchases will not be able to use their monthly AT&T payment to pay for digital content on Google’s app store. Those using this method now can continue to do so, but only until September.
At the moment there is no information as to why that decision was made. Both Google and the carrier are silent about this. However, AT&T is not the only operator to be removed from the Play Store payment system.
At the beginning of the year, Verizon customers also had to deal with news that they would no longer be able to use their subscription to make purchases in the Play Store. At the time, the carrier said in a statement that the withdrawal from the Play Store’s payment methods was a “business decision.”
So with Verizon gone and AT&T on the decline, the only carrier billing supported by the Google Play Store are Boost Mobile, Sprint, T-Mobile, and US Cellular. AT&T and Verizon customers still have the option to use credit and debit cards, as well as PayPal and Google Pay.
To change your payment method, open the Google Play Store app and tap your profile icon in the top right corner. Then choose “Payments & Subscriptions” and tap “Payment Methods.” Then select “Edit payment method”, tap “Edit” on the option you want to change and then choose another payment method. Then tap “Update” to save the change and complete the process.