I need a native Android application that lets customers book online services and pay through Etisalat Direct Carrier Billing, so the entire purchase happens with a single tap on their mobile balance—no cards or external gateways. The flow is simple: browse services, pick an available slot, confirm, and complete payment without leaving the app. The service catalogue and pricing endpoints are already exposed via REST, so the app only has to consume those APIs, present the data with clean Material Design screens, and handle the Etisalat DCB subscription / one-time charge callbacks securely. Deliverables • Full Android source code (Kotlin or Java) and compiled APK • Etisalat DCB sandbox integration fully tested and ready for production switch • Booking module: service list, detail view, slot or date picker, confirmation & receipt • Basic localisation hooks for English and Arabic • README with build instructions, payment credentials setup, and callback formats Acceptance criteria • A booking can be completed end-to-end on a device using an Etisalat SIM without redirecting outside the app • Successful and failed payment states are pushed to the backend via the provided REST callback • App meets Google Play policy, targets at least API 24, and passes Play Protect If you have shipped carrier-billing apps before or worked with Etisalat’s gateway, let me know along with your estimated timeline.