I need an experienced Flutter developer to weave call-masking into my existing mobile app so real phone numbers stay private at every stage of a conversation. The feature must work in both directions—whether the user initiates or receives the call, only a virtual number is ever shown. The app already relies on phone-number verification for sign-in, so your solution should slot neatly into that flow. I’m open to Twilio, Sinch, Plivo or any other proven voice API, as long as the calls remain inside the Flutter experience and the masking bridge is reliable on both Android and iOS. Deliverables • Clean, well-structured Flutter code that handles masked outgoing and incoming calls • Integration with a voice API of your choice, configured for two-way masking • A brief setup guide plus comments in the code so I can maintain it later • End-to-end testing results (or a short demo video) showing the privacy layer working on real devices If you’ve shipped something similar before, let me know—those examples will speed up our decision.