SAN FRANCISCO--(BUSINESS WIRE)--Boku, the global leader in direct carrier billing-based mobile payments, has announced a new partnership to bring direct carrier billing to Google Play™ for Zain subscribers in Saudi Arabia. As smartphone penetration and demand for digital content grows in the Middle East, direct carrier billing is emerging as a key payment method for accessing mobile content across the region. As a result of the partnership, Zain subscribers can use one-tap mobile payments to pu