To upgrade the advertising services within your ringtone app, my approach involves a step-by-step transition from the existing Google Play-services-ads version 19.4.0 to the desired version 22.4.0, ensuring compatibility and optimization. I'll begin with a comprehensive assessment of the app's current ad framework, strategizing a seamless upgrade process that mitigates potential disruptions. Simultaneously, I'll meticulously remove Facebook Ads from the app and integrate Admob ad open, seamlessly replacing Facebook Native Ads with Admob's native ad functionalities. My implementation plan entails thorough testing at each stage to ensure uninterrupted functionality and optimal performance. Reflecting on analogous projects, I've previously orchestrated similar transitions, upgrading ad services within mobile applications while ensuring a smooth migration between versions. Moreover, I've adeptly managed the integration of diverse ad platforms, aligning with the nature of this project and assuring an enhanced user experience. I'm genuinely excited about the prospect of enhancing your ringtone app's advertising services, elevating its performance with the latest Google Play-services-ads version and Admob's native ad features to maximize revenue potential and user engagement.