I’m excited to announce the public release of VoiceBlender — an open source Go service that bridges complex telephony world with the easiness of web development.
Why VoiceBlender?
I’ve been building similar solutions for the last 10–12 years and accumulated all of that experience into this project.
When companies start building voice applications, they usually reach for FreeSWITCH or Asterisk and build around it. These are powerful tools, but they come with real limitations:
- Steep learning curve — dialplans, ESL, AGI, and custom modules take months to master.
- Tightly coupled architecture — business logic ends up tangled with the media server, making changes risky.
- Limited modern protocol support — WebRTC and AI integrations require additional layers and workarounds.
- Difficult to scale — scaling traditional PBX platforms horizontally is an afterthought, not a design goal.
SIP is complex. Building applications that directly talk SIP is hard and sometimes dangerous. Finding good engineers with SIP knowledge can be challenging. VoiceBlender solves many of these issues by hiding the complexity of SIP and RTC behind a RESTful interface to manage calls.
Key Features
- SIP Inbound & Outbound — Originate and receive SIP calls with support for PCMA, PCMU, and Opus codecs.
- WebRTC — Browser-based voice via SDP offer/answer with trickle ICE.
- Multi-Party Rooms — Mix multiple participants in a single room. Join via SIP, WebRTC, or WebSocket.
- TTS & STT — Built-in support for ElevenLabs, Google Cloud, AWS Polly, and Deepgram.
- AI Agent — Attach a conversational AI agent to any leg or room with barge-in support.
- REST API & Webhooks — Full control over legs, rooms, playback, recording, and more.
Getting Started
go build -o voiceblender ./cmd/voiceblender
./voiceblender
The REST API starts on :8080 and SIP listens on :5060. Check the API Documentation for the full endpoint reference.
What’s Next
We’re actively working on additional AI provider integrations, improved recording formats, and clustering support. Stay tuned for more updates.