# Connect FusionPBX with a SIP trunk

> Register a FusionPBX gateway to the PBX with a SIP trunk so it can make and receive calls.

- URL: https://kb.voipcloud.online/au/teams-and-sip/sip-trunking/fusionpbx/
- Section: Microsoft Teams and SIP trunking › SIP trunking
- Type: guide
- Applies to: All countries
- Last reviewed: 2026-11-09

This guide connects FusionPBX to your PBX with a SIP trunk. In FusionPBX, the trunk is a gateway that registers to the PBX with a username and password.

## Before you start

- Order a trunk licence and channels: go to **Services** › **SIP trunking**, set the number of **Channels** (one per simultaneous call), click **Add licence**, tick **Agree to service terms and conditions** and click **Submit order**.
- Have admin access to the FusionPBX web interface.

## 1. Create the SIP trunk in the PBX

1. Go to the **PBX** tab. Drag **SIP trunk** from the **Accept, make and divert calls** group onto the canvas and click the gear icon.
2. Enter a **Name** and set the **Number of channels**.
3. For **Mode**, choose **SIP registration**.
4. Choose a **SIP trunk call plan**. Without one, outgoing calls won't work.
5. Choose the **Caller ID** for outgoing calls, or **Keep originator's caller ID** to use the number FusionPBX sends.
6. Click **Save**.
7. Connect an [Inbound number](https://kb.voipcloud.online/au/pbx/receive-calls/inbound-number/) with the numbers that should ring on FusionPBX to the SIP trunk.
8. Click **Apply configuration**.

Open the trunk's settings again and note the **SIP credentials**: **Domain**, **Username** and **Password**. The **Domain** is shown as server and port, separated by a colon. Also note the **Transport protocol**: TCP, or TLS if **TLS encryption** is turned on in **Settings** › **General**. See [SIP trunk](https://kb.voipcloud.online/au/pbx/accept-make-divert/sip-trunk/) for every setting.

## 2. Add a gateway in FusionPBX

**Note:** Menus can change between versions. If a label is different, check the vendor's own help.

1. In the FusionPBX web interface, go to **Accounts** › **Gateways** and click **Add**.

   ![FusionPBX Gateways page opened from the Accounts menu, with the Add button](https://kb.voipcloud.online/au/images/teams-and-sip/sip-trunking/fusionpbx-gateways.webp)

2. Fill in these fields from the PBX trunk's SIP credentials:

 | FusionPBX field | Enter |
 | --- | --- |
 | **Gateway** | Any name for the gateway. |
 | **Username** | The **Username**. |
 | **Password** | The **Password**. |
 | **From User** | The **Username**. |
 | **From Domain** | The **Domain**, including the port. |
 | **Proxy** | The **Domain**, including the port. Don't leave the port out. |
 | **Register** | **True** |

   ![FusionPBX gateway form with Username, Password, Proxy and Register filled in](https://kb.voipcloud.online/au/images/teams-and-sip/sip-trunking/fusionpbx-gateway-settings.webp)

3. Click **Advanced** to show more fields, and fill in:

 | FusionPBX field | Enter |
 | --- | --- |
 | **Auth Username** | The **Username**. |
 | **Register Transport** | **tcp**, or **tls** if the trunk's **Transport protocol** is TLS. |
 | **Register Proxy** | The **Domain**, including the port. |

   ![FusionPBX advanced gateway fields with Auth Username, Register Transport set to tcp and Register Proxy](https://kb.voipcloud.online/au/images/teams-and-sip/sip-trunking/fusionpbx-advanced-settings.webp)

4. Click **Save** in the top-right corner.
5. Reload the configuration so FusionPBX loads the new gateway.

## 3. Set up routes in FusionPBX

- Add inbound routes for the phone numbers you send to the trunk.
- Add outbound routes that use the new gateway.

## Check it works

1. In the PBX, the SIP trunk's **Status** shows **Online**.
2. Call one of your numbers from a mobile. A FusionPBX extension should ring.
3. Call a mobile from a FusionPBX extension. The mobile should show your caller ID.

If calls fail, check the inbound and outbound routes in FusionPBX. If the trunk stays offline, check the username, password and port: after failed sign-in attempts, the PBX blocks the IP address for 5 minutes. You can check this with **Check IP address for blocking** in the trunk's settings.

## Next steps

- [SIP trunk](https://kb.voipcloud.online/au/pbx/accept-make-divert/sip-trunk/): inbound and outbound rules for numbers and extensions hosted on FusionPBX.
- [Device offline](https://kb.voipcloud.online/au/troubleshooting/device-offline/) if the trunk won't register.