# (Optional) Integrate ZPLS with PSTN

This section provides step-by-step instructions for integrating an SBC with the ZPLS module for PSTN connectivity during survivability events. This process is not required for customers that do not plan to integrate their ZPLS module with an SBC. However, customers that *do* plan on integrating are encouraged to complete this process as soon as possible, prior to any outage occurring.

### Install Zoom’s Certificates on your SBC

To establish a survivability PSTN connection, a SIP trunk must be established between your site’s SBC and the ZPLS module. Prior to beginning this process, the SBC **must**have [Zoom’s Digicert root and intermediate certificates installed](https://support.zoom.us/hc/en-us/articles/360044092031).

### Configure the SBC for Premises Peering (BYOC Setup)

Confirm your SBC meets [minimum requirements](#_5j9072fqrtdk) and is configured for [BYOC premises peering](#_upyv4qcmv0q9).

### Add an SBC to a Site

To begin the PSTN integration process, an SBC must be added to the web portal and associated with the account or a specific site. To add an SBC to your account, perform the following steps:

1. Sign into the Zoom web portal.
2. Under the **Phone System Management** sub-menu, select **Company Info**.
3. **Select the site name** from the list (or click **Account Settings** if a single-site configuration).
4. Select the site’s **Settings** tab.

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5. Locate the **Routing** subsection, and the setting for **Session Border Controllers**. Click **Manage** to load a new page.

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6. On the new page, click the blue **Add** button in the top-left corner to add an SBC.
7. On the following page, populate the following fields:
   1. **Display Name** describes the SBC being added.
   2. Enter a **Public IP** and **Port Number** for the SBC. This should be the public IPv4 address assigned to the SBC and is used to establish a SIP trunk from the cloud.
   3. Enter a **Survivability Public/Private Address** and **Port Number**. This is used to establish a SIP trunk between the ZPLS module and the SBC.

{% hint style="danger" %}
Zoom strongly recommends using a **private** IPv4 address for the above value. A private value can avoid routing unnecessary traffic through the firewall, which may otherwise require complex route reflection rules.
{% endhint %}

8. Continue populating the fields:
   1. Toggle the **In Service** switch to mark the SBC as capable for use.
   2. Enable **Integrate an on-premises PBX**to ensure BYOC numbers can be routed through the cloud under normal operating conditions.
   3. Enable **Send OPTIONS ping messages** to allow account administrators to verify SBC connectivity between the ZPLS module and Zoom Phone cloud.
   4. Click **Save** to complete.

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### Configure a Route Group

Each phone site (or account for single-site deployments) requires two route groups to ensure PSTN connectivity is functional with the ZPLS module.

1. A BYOC route group is required to create a SIP trunk between a Zoom Phone SIP zone and each site’s SBC. When configured, this SIP trunk directs inbound calls made to a BYOC number to the local site during routine (non-survivability) operations.
2. A survivability route group is required for each phone site to direct outbound calls from the ZPLS module to the SBC.

#### BYOC Route Group

To create a BYOC route group between your SBC and Zoom Phone data centers, perform the following steps:

1. Sign into the Zoom web portal.
2. Under the **Phone System Management** sub-menu, select **Company Info**.
3. **Select the site name** from the list (or click **Account Settings** if a single-site configuration).
4. Select the site’s **Settings** tab.

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5. Locate the **Routing** subsection, and the setting for **Route Groups**. Click **Manage** to load a new page.

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6. On the following page, click the blue **Add** button in the top-left corner and a pop-up will appear.
7. Within the pop-up, enter a **Display Name** for the route group and select the **Region** closest to the geographical location of the ZPLS module. **Distribution** should be set to **Sequential**.

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8. Select the **Session Border Controller** added in the previous section.
9. Click **Save**.

#### Survivability Route Group

To create the survivability route group and route outbound calls from the ZPLS module to the SBC, perform the following steps:

1. Repeat steps 1-6 from the previous section.
2. Within the pop-up, enter a **Display Name** for the route group.

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3. Change the **Type** to **Survivability**.
4. Select the **Session Border Controller** added in the previous section.
5. Click **Save**.

### Assign the Survivability Route Group to the ZPLS Module

After the survivability route group is created, it must be assigned to the ZPLS module. To assign the route group, perform the following steps:

1. Under the **Phone System Management** sub-menu, select **Company Info**.
2. Click **Account Settings** in the top-left corner.

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3. On the following screen, locate the **Zoom Node** subsection, and the setting for **Local Survivability**. Click **Manage** to load a new page.

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4. Locate the server to be assigned, click **Assign to** or **Edit**, and a pop-up will appear.
5. Within the pop-up, fill in the **Assign To** fields with the intended site and route group created in the previous section.

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{% hint style="info" %}
The site for this module may have been previously filled out during the [Associate the ZPLS Module with a Site](#_k11n5zxkx1pq) process. If so, click the ellipses box (**...**) and click **Edit**. Re-select the Site and choose the appropriate Route Group.
{% endhint %}

6. Click **OK** when complete to finish.

After completion, the ZPLS module for the site will attempt to establish a TLS connection with the site’s SBC. If the OPTIONS ping is enabled, routine OPTIONS pings will transmit between the two devices for verification and troubleshooting purposes.