I built YakPhone because every SIP app I tried either looked like it was made in 2009 or required sending my calls through someone else's cloud.
The thing I'm most proud of: all AI runs on your device. Whisper transcribes your calls locally. The LLM chat (llama.cpp) never phones home. Your conversations stay yours.
A few things that were fun to build:
SIP: baresip 4.70 + libre, wrapped in Objective-C++. UDP/TCP/TLS registration, multiple accounts. Works with Asterisk, FreePBX, FreeSWITCH, 3CX.
Security / NAT: DTLS-SRTP, SDES, ZRTP for media encryption. STUN and TURN support.
CallKit + PushKit: Native iOS call UI. If you self-host a PBX you can wire up the push relay for incoming call wakeup and missed call notifications.
Video: H.264 via VideoToolbox, picture-in-picture, front/back camera flip mid-call, DTMF.
On-device AI: Whisper model download with real-time call transcription. Q4 quantized LLM for post-call summarization. All inference runs locally — no audio leaves the device.
Free download. One-time Pro purchase for AI features, no subscription.
Happy to answer any technical questions! 🙏
