IP Phone Developer – XML Apps, FastAPI & Twilio

We’re looking for a developer with hands-on experience building applications for IP desk phones, especially Yealink or Grandstream XML Browser interfaces. We have an existing Visual Voicemail system with two implementations: One is live but depends on a third-party service for parts of the phone UI. The other is fully in-house and already supports voicemail listing, playback, save/delete, forwarding, caching, transcription, and AI summaries, but needs production hardening and real-device testing. Stack: Python, FastAPI, PostgreSQL, Redis, React, Twilio, hosted PBX APIs, GitHub. We’re specifically looking for experience with: - IP phone XML applications - Yealink and/or Grandstream - Python / FastAPI - Hosted PBX integrations such as NetSapiens, BroadWorks, Metaswitch, or similar - Twilio Programmable Voice, TwiML, IVR, and webhooks When applying, please include your closest IP phone/XML or telephony project, PBX platforms you’ve worked with, Twilio/IVR experience. Potential for additional VoIP and phone self-service projects if this first engagement goes well.