Voice AI is broken.
Not because the models are bad —
but because access is rationed by wrappers.
Today's "Voice AI platforms" are toll booths.
They:
- Wrap public APIs (OpenAI, Deepgram, Cartesia)
- Add minimal orchestration
- Charge per-minute rent
- Lock you into black boxes
- Sit between you and your users' conversations
At scale, this is insane.
You pay:
- For your LLM
- For your STT
- For your TTS
- For your SIP trunk
- And again — just to connect them
This is not innovation.
It's rent-seeking.
Voice agents hear everything:
- Medical data
- Financial details
- Sales conversations
- Private emotions
- Business secrets
- Where do your calls go?
- Who stores the recordings?
- Who can access the transcripts?
- What happens to the data after the call?
"Trust us" is not a security model.
When you route calls through a managed platform:
- You lose data sovereignty
- You accept their terms
- You hope they're secured
- You pay for the privilege
- You should own your calls — not rent access to them
- You should own your infrastructure — not depend on someone else's
- You should pay for compute — not permission
- Latency matters — and it's determined by your model choices, not our infrastructure
- Interruptions matter — Siphon gives you the controls, you tune them
- Python developers shouldn't be forced into Node or Go to ship voice
- Open source beats black boxes
- Direct integrations beat wrappers
- Standards beat vendor lock-in
Siphon is Sovereign Voice AI.
| Principle | Implementation |
|---|---|
| 🔓 Open Source | Apache 2.0 license — inspect, modify, deploy |
| 🏠 Your Infrastructure | Runs on your cloud, your servers, your LiveKit |
| 💰 No Platform Fees | Pay your AI providers directly, no markup |
| 🔒 No Hidden Routing | Your calls go from SIP → LiveKit → your agent |
| 🔑 No Lock-In | Swap LLMs, STT, TTS providers with config changes |
Not for a platform.
Siphon is not the easiest path.
It is the right one.
If you want convenience, buy a wrapper.
If you want control, use Siphon.
Note: Latency and interruption handling depend heavily on your model choices. Siphon's infrastructure is optimized for sub-500ms latency — but the models you choose determine the final user experience.
Best Overall Stack:
LLM: Groq (Llama 3.3 70B) or Cerebras (Llama 3.1 8B)
STT: Deepgram Nova 3
TTS: Cartesia Sonic or ElevenLabs Turbo- Why: Groq/Cerebras have 200-500ms time-to-first-token (TTFT)
- Latency: ~800ms-1.2s total (STT → LLM → TTS → audio)
- Cost: ~$0.02-$0.05/min (direct provider costs)
Premium Stack:
LLM: OpenAI GPT-4o or Anthropic Claude 3.5 Sonnet
STT: Deepgram Nova 3 or AssemblyAI
TTS: ElevenLabs (standard) or Cartesia Sonic- Why: GPT-4o has excellent conversational ability and function calling
- Latency: ~1.5-2.5s total
- Cost: ~$0.05-$0.12/min (direct provider costs)
Budget Stack:
LLM: DeepSeek V3 or Groq (Llama 3.1 8B)
STT: Deepgram Nova 2
TTS: Cartesia Sonic or OpenAI TTS- Why: DeepSeek is incredibly cheap, Groq has free tier
- Latency: ~1-1.5s total
- Cost: ~$0.01-$0.03/min (direct provider costs)
Global Stack:
LLM: OpenAI GPT-4o or Google Gemini 2.0 Flash
STT: Deepgram Nova 3 (multi-language) or Google STT
TTS: Sarvam AI (Hindi/Indic) or ElevenLabs (multilingual)- Why: Gemini 2.0 Flash excels at multilingual, Sarvam optimized for Indic languages
- Latency: ~1.2-2s total
- Cost: ~$0.03-$0.08/min (direct provider costs)
Power Stack:
LLM: Anthropic Claude 3.5 Sonnet (200k context)
STT: Deepgram Nova 3
TTS: ElevenLabs or Cartesia- Why: Claude 3.5 handles complex multi-step reasoning
- Latency: ~2-3s total (worth it for quality)
- Cost: ~$0.08-$0.15/min (direct provider costs)
For natural barge-in, configure:
Agent(
allow_interruptions=True,
min_interruption_duration=0.08, # 80ms minimum to register
min_endpointing_delay=0.45, # 450ms before detecting turn end
activation_threshold=0.4, # VAD sensitivity (lower = more sensitive)
)Critical for interruptions:
- ✅ Fast LLM TTFT — Groq, Cerebras, GPT-4o mini
- ✅ Streaming TTS — Cartesia, ElevenLabs Turbo
- ✅ Low endpointing delay — 400-600ms sweet spot
| Aspect | Managed Platform (Vapi/Retell/Bland) | Siphon (Self-Hosted) |
|---|---|---|
| Cost (10k minutes) | $500-$3,100 + AI costs | $0 + AI costs ($200-$800) |
| Data Routing | Platform servers → your users | Your servers → your users |
| Vendor Lock-In | Hard (API-specific) | None (swap providers anytime) |
| Observability | Platform dashboard | Full control (your logs, your storage) |
| Customization | Limited to API parameters | Full code access |
| Compliance | Trust their security | You control security |
| Latency | Platform routing overhead | Direct LiveKit connection |
| Scaling | Platform limits | Your infrastructure limits |
You have two paths:
- ✅ Quick to start
- ✅ Managed infrastructure
- ❌ Per-minute fees ($0.05-$0.30/min)
- ❌ Data goes through their servers
- ❌ Limited customization
- ❌ Vendor lock-in
- ✅ No platform fees
- ✅ Full data ownership
- ✅ Complete customization
- ✅ No vendor lock-in
- ❌ Requires setup (LiveKit + SIP)
- ❌ You manage infrastructure
Choose wisely.
Siphon is more than a framework.
It's a statement.
The future of voice AI is sovereign.
- Star us: github.com/blackdwarftech/siphon
- Contribute: Help build the infrastructure for sovereign voice
- Deploy: Run voice agents on your terms
Built with Siphon.
Owned by you.