Support service app use voip sdk

I am looking for a skilled voip developer to integrate own voip sdk and make customization for our support service app ( android- IOS) that offers customers voip services The app should involve real-time connection and use VoIP audio ,chat ,voice messages and geolocation features
Skills and experience required for this project:
- Experience in developing customer service apps
- Proficiency in real-time connection implementation
- Expertise in VoIP audio SDK integration