Contract Engineer for Cloud-Based Phone System Integration

Role Overview

We are seeking an experienced Contract Engineer to integrate a cloud-based phone system using Telnyx into our existing iOS and Android mobile applications. This role demands hands-on expertise with WebRTC, telephony APIs, and mobile application development using React Native and Expo. The ideal candidate will have a proven track record in delivering production-ready phone or VoIP integrations and possess the ability to work independently to design, implement, and stabilize the solution.

Responsibilities

• Design and implement a mobile phone system integration using Telnyx for both iOS and Android applications.
• Build and maintain WebRTC-based calling functionality, including signaling, call handling, and media streams.
• Integrate telephony and phone system capabilities via REST and real-time APIs.
• Implement and maintain mobile features using React Native and Expo.
• Integrate backend communication using tRPC.
• Ensure the reliability, performance, and security of voice and signaling components.
• Troubleshoot and resolve issues related to call quality, connectivity, and device compatibility.
• Collaborate with internal engineering stakeholders to align on architecture and delivery timelines.
• Produce clear technical documentation related to the integration.

Required Skills

• Proven experience integrating telephony or VoIP systems into mobile applications.
• Hands-on experience with Telnyx or similar cloud telephony providers.
• Strong understanding of WebRTC, including signaling, ICE, STUN/TURN, and media handling.
• Experience integrating phone systems via APIs and SDKs.
• Strong proficiency in React Native.
• Experience with Expo in production environments.
• Working knowledge of tRPC for client-server communication.
• Experience deploying and supporting applications on iOS and Android.
• Ability to work independently in a contract-based engagement.

Nice to Have

• Prior experience with call state management, background calling, and push notifications for VoIP.
• Familiarity with mobile audio session management on iOS and Android.
• Experience optimizing call quality and handling edge cases across devices and networks.
• Previous contract or consulting experience delivering defined technical outcomes.