Apple has enabled carrier billing in Austria for Drei customers, Italy for Three customers, and Singapore for M1 Limited customers, expanding upon the feature's existing availability among select carriers in Belgium, Germany, Japan, Norway, Russia, Switzerland, Taiwan, Saudi Arabia, and the United Arab Emirates.
The payment method enables customers to pay for iTunes content, App Store apps, iBooks, and Apple Music subscriptions without needing a credit or debit card, or even a bank account. Instead, purchases are added to a customer's mobile phone bill and paid off at the end of the month.
Apple has a support document explaining how to set up carrier billing on iPhone, iPad, or iPod touch and Mac or PC.
