# Configure AI-to-Live Agent Call Transfers

ElevenAgents provides a built-in feature that allows its AI Agent to transfer an active, answered call to a live human
agent. This is achieved using in-dialog [SIP
REFER](../../voice/inbound-trunks/sip-trunks/call-handling-and-delivery/inbound-call-redirection.html#call-redirection-refer)
signaling, where the AI Agent issues a REFER request during the call to redirect the caller to another destination.

When the transfer is triggered, ElevenAgents sends a SIP REFER request to DIDWW. After validating the request, DIDWW
initiates a new outbound call to the live agent using your configured outbound trunk. To ensure this process works
reliably, both the inbound and outbound SIP trunks must be correctly configured, and ElevenAgents must be set up to
authenticate with DIDWW and send SIP REFER requests.

Note

Ensure that both your inbound and outbound SIP trunks are fully operational before beginning this configuration. See [1.
Route Incoming Calls to ElevenAgents](index.html#elevenlabs-inbound) and [2. Enable Outbound Calling from ElevenAgents
Through DIDWW](index.html#elevenlabs-outbound) for setup instructions.

---



## 1. Configure Outbound SIP Trunk

To enable the **SIP REFER** transfer, the outbound trunk must be configured to accept signaling from **DIDWW Inbound SIP
IPs**.
This ensures that when a call is transferred, DIDWW can initiate a new outbound call (to the live agent) using the same
trunk, authenticated with the credentials from your inbound trunk.



### Before You Begin

At least one [Outbound Trunk](index.html#elevenlabs-outbound) is required, with **Authentication method** set to
**Credentials & IP-Based**.

### Step 1: Edit Outbound SIP Trunk

1. In the [DIDWW User Panel](https://my.didww.com/#/trunks), open the **Voice** section from the left navigation menu.
2. Select **Outbound Trunks**.
3. Locate your **ElevenLabs** trunk in the list.
4. Click the trunk name or the Actions (⋯) icon, then select **Edit**.

![Editing the Outbound Trunk for ElevenLabs AI-to-Agent Transfers](../../_images/edit_outbound_trunk_elevenlabs.png)


Fig. 1. Editing the Outbound Trunk for ElevenLabs AI-to-Agent Transfers

### Step 2: Configure Allowed SIP IP Addresses

1. In the **Edit Outbound Trunk** window, locate the **Allowed SIP IP addresses** field.
2. Add [DIDWW inbound SIP IPs](../../voice/inbound-trunks/sip-trunks/sip-connectivity-reference.html#service-did-sip), such as IPv4 `46.19.210.14` and IPv6 `2a01:ad00:2:14::14`, and ensure the correct **ElevenLabs SIP IPs** are also included.
3. Click **Submit** to save the changes.

Note

ElevenLabs SIP traffic originates from IP ranges that may vary depending on your plan or region.
Refer to the official ElevenLabs documentation for the most up-to-date information:
[ElevenLabs SIP Trunking IP Information](https://elevenlabs.io/docs/agents-platform/phone-numbers/sip-trunking)

Warning

You can allow all traffic by adding `0.0.0.0/0`, which removes all IP restrictions.
Although SIP Digest Authentication will still verify requests using valid credentials, this configuration is **not
recommended**.
Always restrict access to known ElevenLabs IPs whenever possible.

![Allowing inbound DIDWW SIP IPs on the outbound trunk](../../_images/uc1.png)


Fig. 2. Allowing inbound DIDWW SIP IPs on the outbound trunk

### Step 3: Copy Credentials From Outbound Trunk

Copy the outbound trunk authentication credentials before configuring the inbound trunk. Keep these credentials
available for the inbound trunk authorization and ElevenAgents configuration steps.

1. On the [Outbound Trunks](https://my.didww.com/#/outbound_trunks) page, locate your **ElevenLabs** outbound trunk.
2. Click the **key icon** under the **Credentials** column to open the **Credentials** window.

![Opening the Outbound Trunk Credentials in the DIDWW User Panel](../../_images/outbound5.png)


Fig. 3. Opening the Outbound Trunk Credentials in the DIDWW User Panel

3. In the **Credentials** window, copy the **Username** and **Password**. Click the **eye icon** to reveal the password if it is hidden.

![Copying the Outbound Trunk Username and Password](../../_images/3copy_out_credentials2.png)


Fig. 4. Copying the Outbound Trunk Username and Password



---

## 2. Configure Inbound SIP Trunk

To enable the **SIP REFER** transfer process, the inbound trunk must be configured to accept and authenticate in-dialog
REFER requests from **ElevenAgents** through DIDWW.
This ensures that when an active call is transferred, DIDWW can validate the REFER request using your inbound trunk
credentials and then initiate a new outbound call to the live agent via your **Outbound Trunk**.



### Before You Begin

At least one [Inbound SIP Trunk](index.html#elevenlabs-inbound) is required. This trunk will be used to receive inbound
calls from **ElevenLabs** and must be properly linked to your **Outbound Trunk** for SIP REFER call transfers to
function correctly. Have the [outbound trunk credentials](#elevenlabs-call-transfer-outbound-trunk-copy-credentials)
available before continuing.

### Step 1: Edit Inbound SIP Trunk

1. In the [DIDWW User Panel](https://my.didww.com/#/trunks), open the **Voice** section from the left-hand navigation menu.
2. Select **Inbound Trunks**.
3. Locate your **ElevenLabs** inbound trunk in the list.
4. Click the **Actions (⋯)** icon, then select **Edit**.

![Editing the Inbound Trunk for ElevenLabs AI-to-Agent Transfers](../../_images/edit_inbound_trunk_elevenlabs.png)


Fig. 5. Editing the Inbound Trunk for ElevenLabs AI-to-Agent Transfers

### Step 2: Configure the Network Protocol

Important

The **Network protocol** setting in your inbound trunk must **match** the configuration used in your outbound trunk.
This ensures proper communication between trunks during **SIP REFER** call transfers.
For example, if your outbound trunk is configured for **IPv4 only**, the inbound trunk must also use **IPv4 only**.
A mismatch between IP versions will prevent call transfers from completing successfully.

1. In the **General** tab of the **Edit Inbound SIP Trunk** page, locate **Network Protocol**.
2. Select the same IP version as configured in your outbound trunk, as described in [Step 2 of the Outbound Trunk setup](#elevenlabs-call-transfer-outbound-trunk-configuration-step2).

![Configuring Network Protocol for Inbound SIP Trunk](../../_images/network_protocol_inbound_sip_trunk.png)


**Fig. 6.** Configuring the Network Protocol for the Inbound SIP Trunk (AI-to-Agent Transfer)

### Step 3: Add Outbound Trunk Credentials to Inbound Trunk Authorization

Apply the credentials copied from the **Outbound Trunk** to the inbound trunk authorization settings.

1. Open the **Authorization** tab.
2. Turn on **Enable Authorization**.
3. Paste the **Auth User** and **Auth Password** values that you copied from [Step 3: Copy Credentials From Outbound Trunk](#elevenlabs-call-transfer-outbound-trunk-copy-credentials).

Note

Enabling authorization ensures that DIDWW validates all SIP REFER requests using the credentials from your outbound
trunk.
This step is required for successful AI-to-Live Agent call transfers between **ElevenLabs** and **DIDWW**.

![Inbound SIP Trunk Authorization settings](../../_images/4_paste_authentication.png)


Fig. 7. Configuring authorization on the Inbound SIP Trunk

### Step 4: Configure Signalling Settings

To enable in-dialog SIP REFER transfers between inbound and outbound trunks, adjust **Max Transfers** in the
**Signalling** tab.

1. In the **Edit Inbound SIP Trunk** page, open the **Signalling** tab.
2. Locate **Max Transfers**.
3. Set this value to **1** or higher to allow in-dialog SIP **REFER** transfers.
4. Click **Submit** to save the configuration.

Important

Setting **Max transfers** to `0` disables call transfers.
To ensure successful AI-to-Live Agent transfers, this value must be at least **1**.

![Inbound SIP Trunk Signalling tab with Max Transfers](../../_images/5_inbound_advanced_settings.png)


Fig. 8. Inbound SIP Trunk Signalling tab with Max Transfers configured for REFER transfers



---

## 3. Configure ElevenAgents

To complete the AI-to-Live Agent transfer setup, you must configure ElevenAgents to authenticate with DIDWW and enable
the **Transfer to Number** function within your AI Agent.



### Before You Begin

- At least one [Imported DIDWW Number](index.html#elevenlabs-configure-number) must be available in your **ElevenLabs** account and linked to a valid SIP Trunk connection.
- You will also need the **Outbound SIP Trunk credentials** obtained in [Step 3: Copy Credentials From Outbound Trunk](#elevenlabs-call-transfer-outbound-trunk-copy-credentials).

### Step 1: Update SIP Trunk Authentication for Your Phone Number

To allow **ElevenAgents** to authenticate inbound calls from **DIDWW** and enable call transfers, update the SIP Trunk
configuration for your imported DIDWW number.

1. In the ElevenAgents Dashboard, open the **Phone Numbers** menu, or click this direct link: [ElevenLabs Phone Numbers](https://elevenlabs.io/app/agents/phone-numbers).

![Accessing the Phone Numbers section](../../_images/uc9.png)


Fig. 9. Accessing the Phone Numbers section

2. Select your imported **DID Number**, click on it to open the **Number Details** page, and then click **Edit**.

![Editing the imported DIDWW phone number](../../_images/uc10.png)


Fig. 10. Editing the imported DIDWW phone number

3. In the Edit SIP trunk form **Inbound Configuration**, under **Authentication (Optional)** section, enter the credentials copied from your DIDWW outbound trunk, as described in [Step 3: Copy Credentials From Outbound Trunk](#elevenlabs-call-transfer-outbound-trunk-copy-credentials).

   - **SIP Trunk Username:** Enter the outbound trunk username
   - **SIP Trunk Password:** Enter the outbound trunk password
4. Click **Update** to save the SIP trunk configuration.

![Entering DIDWW SIP trunk authentication credentials in ElevenLabs](../../_images/uc11.png)


Fig. 11. Configuring inbound SIP authentication using DIDWW credentials

### Step 2: Configure Voice Agent

1. In the ElevenAgents Dashboard, edit any of your existing **Agents** which will be used to transfer the call.

![Selecting the Voice Agent in ElevenLabs](../../_images/uc5.png)


Fig. 12. Selecting the Voice Agent in the ElevenLabs dashboard

2. Open the **Tools** menu.
3. In the right-side panel, locate the **System tools** section.
4. Find the **Transfer to number** option and enable the setting.
5. Click the **gear icon** next to **Transfer to number** to open its configuration panel.

![Enabling Transfer to number tool](../../_images/uc6.png)


Fig. 13. Enabling the Transfer to number tool in the ElevenLabs Agent configuration

6. In the **Transfer to Number** settings, locate the **Human Transfer Rules** section and fill in the following details:

   - **Transfer type:** Select `SIP REFER` - this defines the transfer method.
   - **Destination type:** Select `SIP URI` - specifies the format of the destination address.
   - **SIP URI:** Enter the SIP address where the call should be transferred to a live person, for example: `sip:+1234567890@fra.eu.out.didww.com`.
   - **Condition:** Enter the condition text that triggers the transfer, for example: `when a caller asks to be transferred to a live person`.
7. Click **Save** in the **Transfer to Number** settings form to confirm your Human Transfer Rules.

![Saving Transfer to Number tool configuration](../../_images/uc7.png)


Fig. 14. Saving the Transfer to Number configuration in the rule editor

8. Finally, click **Publish** on the main **Voice Agent** page to apply all changes.

Important

Ensure that your Voice Agent is **published** and shows a **Live** status in ElevenLabs before testing call transfers.
SIP REFER transfers may fail if the agent is not live.

![Saving the updated Voice Agent configuration](../../_images/uc8.png)


Fig. 15. Saving the updated Voice Agent configuration

### Step 3: Make a Test Call and Verify Call Transfer

Once all configurations are complete, perform a test call to ensure that the **AI-to-Live Agent SIP REFER transfer**
works correctly.

1. Place a call to your **DIDWW number** that is routed to your **ElevenAgents AI agent**.
2. Interact with the AI Agent and trigger the **transfer condition** (for example, ask "Can I speak to a live agent?").
3. Confirm that the call is successfully transferred to the live person and two-way audio is established.

Note

Review the [Inbound](../../logs-analytics/call-logs/inbound-logs.html#inbound-cdr-logs) and
[Outbound](../../logs-analytics/call-logs/outbound-logs.html#outbound-cdr-logs) **CDR Logs** to verify call flow details
and confirm successful completion.
If you experience any issues during testing or call transfers, please contact **DIDWW Support** at
[support@didww.com](mailto:support%40didww.com) for further assistance.

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