Android Walkie Talkie App Development

I'm looking for an experienced Android app developer to create an application similar to a walkie talkie for public use.

Key Functionalities:
- Instant voice calls: Users should be able to communicate with each other instantaneously, nearly replicating the realtime conversation experience provided by a traditional walkie talkie.

Ideal Candidate's Skills:
- Strong proficiency in Android app development.
- Demonstrated experience in developing audio interface applications.
- Understanding of protocols for real-time communication.
- Familiarity with best practices for public use applications.

I anticipate significant public use, so the application must be robust, user-friendly, and able to handle potentially high traffic volumes with ease.