ESP32 Firmware Developer VoIP

**This need to be an extremely fast turnaround.** We're building a screenless voice communication device for kids, built on ESP32. We have a working prototype that can make and receive calls. Looking for an embedded/firmware developer to help push the prototype further. What's working ESP32-based device making real calls via SIP Basic audio in/out Core call flow functional What we need help with Latency — end-to-end delay is too high. Get it under 150ms. Start with OPUS codec and jitter buffer tuning. Echo — calls have echo. Implement AEC (look at esp-sr, built into ESP-IDF). Contact storage — need to store a small list of names and numbers on-device via a config file (SPIFFS or NVS). On-device UI to scroll and select. ESP32-to-ESP32 calling — alongside calling real numbers, add support for device-to-device calls over SIP across different WiFi networks. This means setting up a SIP proxy (Kamailio) on a VPS and registering each device to it. Stack ESP32 (ESP-IDF) SIP / VoIP Ideal candidate Strong ESP32 / ESP-IDF experience Comfortable with SIP/VoIP Has done audio work on embedded hardware before