Android App with PJSIP java. Expert only

I am looking for an expert Android app developer with experience in PJSIP java to FIX a voice calling app. The app is done but has some errors. I need someone who has worked and is an expert with PJSIP and java on Android

Ideal Skills and Experience:
- Strong proficiency in Android app development
- Expertise in PJSIP java
- Experience in creating voice calling apps
- Ability to create a visually appealing and interactive UI design
- Strong problem-solving skills
- Attention to detail and ability to follow a detailed list of requirements.