Mobile Chat App Development

I'm seeking a professional mobile app developer to create a chat application exclusively for Android. The app will heavily rely on phone number verification for user authentication.

Key Requirements:
- Extensive experience in Android mobile app development
- Proficient in implementing secure phone number verification systems
- Previous work with chat applications is a plus.

The ideal freelancer will be able to deliver a user-friendly, secure and innovative mobile chat application. Please include relevant portfolio pieces in your application.