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May 27, 2026 · 7 min read
Telephony is the layer that connects your AI agent to the real phone network. Unpod abstracts away the complexity of SIP, PSTN, and WebRTC - but understanding how the pieces fit together helps you configure it correctly and debug issues faster.

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The Three Components

Unpod telephony has three core concepts: 
Phone Number → Bridge → Provider → Agent
ComponentWhat It IsExample
Phone NumberA real PSTN/VoIP number+1 415 555 0100
BridgeRouting config linking number + provider + agentsupport-bridge
ProviderVoice infrastructure that handles mediaLiveKit, Vapi

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Providers: The Voice Infrastructure

Providers handle the actual audio - WebRTC media servers, transcription, and TTS streaming.

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LiveKit

LiveKit is an open-source, WebRTC-based media server. Unpod’s real-time voice pipeline runs on LiveKit.
  • Sub-300ms end-to-end latency
  • Can be self-hosted (cost control at scale)
  • Supports SIP trunking for PSTN connectivity
  • Best for: developers who want full control, self-hosted deployments

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Vapi

Vapi is a hosted voice AI infrastructure platform.
  • Fully managed - no infrastructure to run
  • Built-in SIP trunking and number management
  • Simplified setup for faster time to production
  • Best for: teams that want managed infra without ops overhead

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Bridges: The Routing Layer

A Bridge is a named configuration that connects:
  • One provider (LiveKit or Vapi)
  • One or more agents
  • One or more phone numbers
Think of it as a switchboard. When a call arrives at a number, the bridge decides which agent handles it.

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Creating a Bridge via Dashboard

Go to Dev Platform → Telephony → Bridges → Create Bridge: 
{
  "name": "support-bridge",
  "provider": "livekit",
  "agent_handle": "aria-support",
  "inbound_enabled": true,
  "outbound_enabled": true
}

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Creating a Bridge via API

curl -X POST https://api.unpod.ai/api/v1/bridges/ \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "support-bridge",
    "slug": "support-bridge",
    "provider_id": 1,
    "agent_handle": "aria-support"
  }'

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Phone Numbers

Unpod provisions real phone numbers through your connected SIP provider. Numbers are then assigned to bridges.

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Number Types

TypeDescriptionUse Case
Local DIDLocal area code numberCustomer support, sales
Toll-Free800/888/877 numbersEnterprise support lines
InternationalNon-US numbersGlobal operations

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Provisioning a Number

curl -X POST https://api.unpod.ai/api/v1/numbers/ \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "country": "US",
    "area_code": "415",
    "bridge_slug": "support-bridge"
  }'
The number is immediately active and routed to your bridge once assigned.

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Call Flow: What Happens on an Inbound Call

  1. Caller dials your number
  2. SIP provider receives the call, looks up the number’s bridge assignment
  3. Bridge routes call to the configured provider (LiveKit/Vapi)
  4. Provider streams audio to the Unpod voice pipeline
  5. Voice pipeline runs: STT → LLM (with your agent config) → TTS
  6. Audio streams back to caller in real time
  7. Call ends, transcript and metadata written to Call Logs
Total setup latency target: under 300ms from first word to agent response start.

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Outbound Calls

For outbound (agent-initiated) calls, create a Task via API: 
curl -X POST https://api.unpod.ai/api/v1/tasks/ \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "agent_handle": "aria-support",
    "phone_number": "+14155550100",
    "bridge_slug": "support-bridge",
    "space_token": "sp_abc123"
  }'
Unpod dials the number, connects it through the bridge, and the agent begins the conversation.

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Multi-Agent Routing

One bridge can route to different agents based on custom logic. Use the API to update bridge routing dynamically: 
curl -X PATCH https://api.unpod.ai/api/v1/bridges/support-bridge/ \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "agent_handle": "billing-agent"
  }'
Combine this with your own IVR or pre-call webhook to build intelligent call routing before the AI agent picks up.

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Debugging Common Issues

SymptomLikely CauseFix
Call connects but agent doesn’t respondProvider not reachable or misconfiguredCheck LiveKit URL and API key in env
Number provisioning failsNo SIP provider connected to bridgeConnect a provider first
High latency on first wordTTS model cold startUse a faster TTS model (OpenAI TTS > ElevenLabs for latency)
Call drops after 30sWebRTC ICE timeoutCheck firewall rules for UDP 10000-60000

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What’s Next

Telephony API Reference

Full API reference for bridges, numbers, and providers.

Dev Platform: Telephony

Dashboard walkthrough for telephony setup.

Providers Overview

Configure and manage voice infrastructure providers.

Create a Task (Outbound Call)

Trigger outbound AI calls via API.