Call transfer agent

Transfer an active Vobiz call to any E.164 phone number via SIP REFER from inside a LiveKit AI voice agent - full code, payloads, and trunk setup.

Transfer an active call to any E.164 phone number or department via SIP REFER from a LiveKit AI agent.

View on GitHub

Clone and run the full working example

Getting started

git clone https://github.com/vobiz-ai/Vobiz-Livekit-Call-Transfer-Example.git
cd Vobiz-Livekit-Call-Transfer-Example
pip install -r requirements.txt
python agent.py dev

Overview

The AI agent handles the conversation and, when instructed, performs a cold SIP REFER transfer to any phone number. The agent constructs the SIP URI dynamically - the caller is transferred and the agent disconnects.

How it works

1. Caller requests a transfer (e.g. “Transfer me to sales” or “Transfer me to [phone]”).
2. The agent calls the transfer_call function tool.
3. The agent sends a SIP REFER to sip:[phone]@your-vobiz-domain.
4. Vobiz routes the call to the destination.
5. The agent leaves the room - the transfer is complete.

Agent function tool

@llm.function_tool(description="Transfer the caller to an E.164 phone number directly")
async def transfer_call(context: llm.FunctionContext, phone_number: str):
    sip_uri = f"sip:{phone_number}@{VOBIZ_SIP_DOMAIN}"
    await context.room.local_participant.perform_rpc(
        destination_identity="sip",
        method="transfer",
        payload=sip_uri
    )

Preset department transfers

Configure preset destinations in .env and map them to named tools:

Command	Destination
”Transfer to billing”	BILLING_NUMBER
”Transfer to support”	SUPPORT_NUMBER
”Transfer me to [number]“	Any E.164 number

Environment variables

.env

LIVEKIT_URL=wss://your-project.livekit.cloud
LIVEKIT_API_KEY=APIxxxxxxxxxxxxx
LIVEKIT_API_SECRET=secretxxxxxxxxxx
VOBIZ_SIP_DOMAIN=your-domain.sip.vobiz.ai
OPENAI_API_KEY=sk-...
BILLING_NUMBER=+919XXXXXXXXX
SUPPORT_NUMBER=+919XXXXXXXXX