# Add an Onsite Proxy Instance

An Onsite Proxy links IP phones on a local network back to your Cloud Voice PBX (Private Branch Exchange, the system that routes your calls). Before you can install and connect a proxy in the field, you first register an instance on the PBX itself. Doing so generates the connection details you'll enter later when you set the proxy up.

## Before you begin

Your Cloud Voice PBX must be running firmware **84.23.0.24** or later.

## Instance limit

A PBX accepts up to **100** Onsite Proxy instances by default.

:::note
Need more than 100? Reach out to your service provider to have the limit raised.
:::

## Add the instance

1. Sign in to the PBX web portal and go to **System > Onsite Proxy**, then click **Add**.

2. Fill in the **Basic** section:

   ![Basic settings for a new Onsite Proxy, showing the name and platform fields](/images/pbx/add-onsite-proxy-basic.png)

   1. In **Name**, type a label that will help you recognize this instance later.

      :::tip
      With up to 100 instances allowed on one PBX, a consistent naming convention (for example, the site or location the proxy serves) makes the list far easier to scan later.
      :::

   2. From the **Platform** drop-down, choose **Linux** (the operating system of the host where the proxy software will run).

3. In the **Audio RTP Passthrough** section, turn the feature on or off to suit your deployment. RTP (Real-time Transport Protocol) is what carries the live voice of a call, so this setting decides which path that audio takes.

   ![The Audio RTP Passthrough toggle in the Onsite Proxy settings](/images/pbx/add-onsite-proxy-rtp-setting.png)

   - **Enabled**: Calls between phones registered through the same Onsite Proxy carry their RTP audio directly, peer to peer, without routing through the PBX or the proxy.

     :::note
     Audio RTP Passthrough cannot be applied in every call scenario. Review the restrictions on Audio RTP Passthrough before relying on it.
     :::

   - **Disabled**: RTP audio for those same calls is relayed through the PBX instead.

4. Click **Save**, then **Apply**.

## Result

The new instance appears in the Onsite Proxy list with its connection details filled in automatically: a connection address, a UUID (Universally Unique Identifier, the ID that identifies this proxy), and a secret key.

![The Onsite Proxy list with an instance and its generated connection details](/images/pbx/add-onsite-proxy-list-cloud.png)

:::caution
Record the connection address, UUID, and secret key now. You'll need all three when you configure the Onsite Proxy on its host. The secret key authenticates the proxy, so treat it like a password and keep it confidential.
:::

## What's next

[Install the Onsite Proxy and connect it to the PBX](/pbx/onsite-proxy-guide/install-onsite-proxy/).