Call transfers

A transfer hands a live call from the agent to a person: your sales desk, a support line, a SIP extension in your PBX, or a Human Operators queue in Callers. Use transfers when a contact is ready to buy, asks for a human, or needs help the agent shouldn’t give. Callers supports two kinds of transfer:

Type	What happens	Use it when
Cold transfer	The agent says its transfer phrase and connects the call. The receiver starts with no context.	The receiver doesn’t need background, or the line is a general queue.
Warm transfer	Callers generates a short spoken summary of the conversation and plays it during the handoff.	The receiver should know who’s calling and why before they speak.

Add a transfer to your script

Add a Call Transfer step

In the script editor, add a Call Transfer step where the agent should hand off, for example in a block the agent reaches when the contact asks for a human.

Write the transfer phrase

In Call Transfer Phrase, write what the agent says before connecting, for example: “I’ll connect you with a specialist now. Please hold for a moment.”

Choose the destination

Use the Phone / SIP tab for a number or SIP address, or the Human operator tab for a queue. See Destinations.

Choose the caller ID

Set Caller ID for Forwarded Call. See Caller ID.

Optional: turn on Warm Transfer

Turn on Warm Transfer and configure the handoff message. See Warm transfer.

Test

Save and make a test call that reaches the transfer step. Make sure the destination answers.

Make the conditions for a transfer explicit in the script, for example a scenario triggered by “Can I talk to a person?”. You can also transfer automatically when a guardrail is triggered.

Destinations

Destination	How to enter it	Example
Phone number	An international number in E.164 format on the Phone / SIP tab.	`+14155550123`
Contact field	A variable on the Phone / SIP tab. Callers resolves it per contact, for example to the contact’s account manager.	`{{account_manager_phone}}`
SIP URI	A SIP address starting with `sip:` on the Phone / SIP tab. Use this to reach an extension or queue in your own PBX.	`sip:sales@pbx.example.com`
Human operator queue	A queue selected on the Human operator tab. The call rings operators who are signed in to Callers.	Support queue

Callers detects the type from what you type: a value with {{ }} is a contact field, a value starting with sip: is a SIP URI, and a value starting with a digit or + is a phone number.

Transfers to SIP URIs need a SIP integration. Human operator queues are set up on the Human Operators page.

Caller ID

Caller ID for Forwarded Call decides which number the receiver sees:

Option	The receiver sees	Best for
Agent’s number (default)	The number the agent called from or was called on.	Receivers who should know the call came through the AI agent.
Contact’s number	The contact’s own number.	Teams that want to call the contact back directly or match the caller in their CRM.

Showing the contact’s number on an outbound leg depends on your carrier allowing it. Some carriers reject or overwrite caller IDs that don’t belong to your account. Test before you rely on it.

With Send SIP Headers on (the default, under General Settings → Technical Settings), Callers adds the contact’s variables as custom SIP headers on outbound calls and transfers, so your PBX can screen-pop the contact’s details.

Warm transfer

With Warm Transfer on, Callers writes a short summary of the conversation when the transfer starts and plays it as audio during the handoff.

Configure the handoff message

In the Call Transfer step:

Setting	Options	What it does
Handoff prompt	Free text, supports variables	Tells the AI what to include in the summary, for example “Summarize the caller’s issue, their account number, and what they’ve already tried in two sentences.”
Play warm transfer message to	Receiver only, Both parties (default)	Receiver only plays the summary to the receiver before the contact is connected. Both parties plays it after both are connected, so the contact hears it too.
When to play handoff message	When call is connected (default), When ⁕ is pressed	Shown for Both parties. With When ⁕ is pressed, the summary plays only when the receiver presses the star key, so they can greet the contact first.

For calls made without SIP (for example, on Twilio numbers), the handoff message can only play to the receiver as soon as the call is connected, and it isn’t included in the call recording. Both parties and When ⁕ is pressed need SIP.

Receiver only is not recommended when the destination is a call queue or IVR: the message may play before a person answers. Use Both parties with When ⁕ is pressed, or trigger the summary with the API.

Write a good handoff prompt

Ask for one to three sentences. Long summaries delay the conversation.
Name the facts the receiver needs: the contact’s name, the reason for the call, and anything already collected.
Reference variables for exact values, for example {{order_id}}, rather than relying on the AI to repeat them.

Play the summary with the API

If your own phone system decides when the receiver is ready, for example when an agent in your contact center accepts the call, play the warm transfer summary with the API at that moment. The Subaccounts and SIP API guide shows the full flow.

string

required

The session ID of the original call (the sessionId field in webhook payloads).

boolean

default:"false"

true plays the summary only to the receiver. false plays it to both the receiver and the contact.

curl -X POST https://api.callers.ai/call/SESSION_ID/warm-transfer-summary \
  -H "Authorization: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "agentOnly": true }'

await fetch(
  `https://api.callers.ai/call/${sessionId}/warm-transfer-summary`,
  {
    method: "POST",
    headers: {
      Authorization: process.env.CALLERS_API_KEY,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ agentOnly: true }),
  }
);

import os
import requests

requests.post(
    f"https://api.callers.ai/call/{session_id}/warm-transfer-summary",
    headers={"Authorization": os.environ["CALLERS_API_KEY"]},
    json={"agentOnly": True},
)

The endpoint works only for calls made through SIP, and only for calls whose transfer step has Warm Transfer on. It returns 404 if no summary exists for the session. Add the x-sub-organization-id header for calls in a sub-account.

Transfer to a human operator queue

Choose the Human operator tab in the Call Transfer step and Select a queue. The call rings operators who are available in Callers, using the queue’s ring strategy. With Warm Transfer on, the summary is delivered to the operator only. See Human Operators to create queues, set ring strategy and timeouts, and handle calls in the browser.

SIP REFER

By default, Callers bridges the transferred call and stays on the line, which keeps recording, warm transfer, and transfer tracking working. For SIP trunks, Callers can instead hand the call to your carrier with SIP REFER and drop off immediately. With SIP REFER:

The call isn’t recorded after the transfer.
Callers can’t tell whether the transfer was answered.
Warm transfer, handoff messages, and any post-transfer logic don’t run.

SIP REFER is set per SIP carrier and applies to every transfer routed through it. Contact support@callers.ai to turn it on.

Recording and limits during transfers

Recording. By default the recording continues after the transfer. Turn on Stop Recording When Call Is Transferred under General Settings → Technical Settings to stop it at the handoff. See Call recording and limits.
Duration. Transferred calls get an extra 150 minutes on top of the agent’s maximum call duration.

Track transfers

The call’s events and transcript show when the transfer happened.
Webhooks send FORWARDED when the call is transferred and FORWARDED_CALL_FINISHED when the transferred leg ends. The payload’s forwardInfo object holds the details.
You can get a notification when a forwarded call isn’t answered. See Notifications.

Troubleshooting

The transfer fails immediately

Check that the number is in E.164 format (with + and country code) and that your telephony provider allows calls to that destination. For contact fields, check that the variable has a value for the contact.

The receiver hears the summary before anyone answers

The destination is probably a queue or IVR and the summary is set to Receiver only. Switch to Both parties with When ⁕ is pressed, or trigger the summary with the API.

The contact's number isn't shown to the receiver

Your carrier may not allow caller ID that doesn’t belong to your account. Use Agent’s number, or ask your carrier to allow it.

The recording stops at the transfer

Check Stop Recording When Call Is Transferred, and whether your SIP carrier uses SIP REFER, which always ends the recording at the transfer.

Human Operators

Queues and browser calling for your team.

Steps

All step types in the script editor.

Instructions and guardrails

Transfer automatically when a guardrail triggers.

SIP integration

Connect your own SIP trunk.

Troubleshooting

Transfers that fail, drop, or ring the wrong destination.

Get started

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Channels

Contacts and outreach

Results and analytics

Human operators

Best practices

Account and administration

Enterprise

Resources

Add a transfer to your script

Destinations

Caller ID

Warm transfer

Configure the handoff message

Write a good handoff prompt

Play the summary with the API

Transfer to a human operator queue

SIP REFER

Recording and limits during transfers

Track transfers

Troubleshooting

Human Operators

Steps

Instructions and guardrails

SIP integration

Troubleshooting

​Add a transfer to your script

​Destinations

​Caller ID

​Warm transfer

​Configure the handoff message

​Write a good handoff prompt

​Play the summary with the API

​Transfer to a human operator queue

​SIP REFER

​Recording and limits during transfers

​Track transfers

​Troubleshooting

​Related

Human Operators

Steps

Instructions and guardrails

SIP integration

Troubleshooting

Add a transfer to your script

Destinations

Caller ID

Warm transfer

Configure the handoff message

Write a good handoff prompt

Play the summary with the API

Transfer to a human operator queue

SIP REFER

Recording and limits during transfers

Track transfers

Troubleshooting

Related