> For the complete documentation index, see [llms.txt](https://support.portsip.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.portsip.com/portsip-communications-solution/configuring-sip-trunks/siptrunk-sip-trunk/configuring-siptrunk-ip-authentication-trunk.md).
# Configuring SIPTRUNK IP Authentication Trunk
Before proceeding with trunk configuration, ensure that you have purchased at least one DID on the [SIPTRUNK ](https://www.siptrunk.com)platform.
***
### SIPTRUNK Setup Guide
To enable inbound calling, you must first complete the required configuration on the SIPTRUNK platform.
1. Sign in to your [SIPTRUNK ](https://login.siptrunk.com/)account.
2. Your SIP trunk will also need to be configured via the customer portal. Refer to this article on [How to Set Up IP Auth](https://support.siptrunk.com/hc/en-us/articles/38765554523547) for complete details.
**IMPORTANT**: You must implement the following whitelisting requirements detailed in the article [Interconnecting with SIPTRUNK](https://support.siptrunk.com/hc/en-us/articles/38762945316379).
Once completed, continue with the trunk configuration in PortSIP PBX.
***
### Configure a SIPTRUNK IP Authentication Trunk in PortSIP PBX
You can configure SIPTRUNK as an **IP-Based Trunk** at the **system administrator** level. After configuration, this trunk can be shared with one or more tenants.
***
#### Step 1: Create the IP-Based Trunk
1. Sign in to the PortSIP PBX Web Portal as a System Administrator.
2. Navigate to **Call Manager > Trunks**.
3. Click **Add**, then select **IP Based Trunk**.
***
#### Step 2: Enter Trunk Details
Configure the trunk with the following settings:
* **Name**: Enter a friendly name for the trunk (for example, `SIPTRUNK Trunk`)
* **Brand**: Select **SIPTRUNK**
Click **Next** to continue.
***
#### Step 3: Configure Trunk Options
* **Max Concurrent Calls**\
Set the maximum number of concurrent calls allowed on this trunk. Adjust this value based on your SIPTRUNK subscription and expected traffic.
> ❗**Recommendation**\
> Keep the default values for other options unless you have specific requirements.
Click **Next** to continue.
***
#### Step 4: Assign the Trunk to Tenants and Configure the DID Pool
1. Assign the trunk to one or more **tenants**.
2. Configure the **DID Pool**(DID numbers) using the SIPTRUNK DIDs you purchased.
> ❗**Important**
>
> A DID number can be assigned to **only one tenant**.
A tenant assigned to this trunk can:
* Use **only** the DID numbers defined in the **DID Pool**
* Create **inbound and outbound routing rules** based on the assigned DID numbers
* Configure **outbound caller IDs** for extensions using the assigned DID numbers
***
**DID Pool Format Examples**
The DID Pool can include a single number, multiple numbers, or number ranges, separated by semicolons.
For example:
```
16468097065
16468097065;16468097066
16468097065-16468097066;16468097069
16468097065-16468097066;16468097070-16468097080
```
***
#### Step 5: Save the Configuration
1. Click **OK** to save the trunk configuration.
***
### Expected Result
* The [SIPTURNK ](https://www.siptrunk.com)P-based trunk is successfully created.
* The trunk status displays **Registered**\
\&#xNAN;*(IP-Based Trunks always show “Registered” in PortSIP PBX)*.
* Assigned tenants can immediately use the configured DIDs for inbound and outbound calls.
***
> ❗**Note**\
> Ensure that SIPTRUNK allows traffic from your PBX IP address when using IP authentication.
Now you can follow the article on [Configuring inbound and outbound calls](/portsip-communications-solution/configuring-sip-trunks/siptrunk-sip-trunk/configuring-outbound-and-inbound-calls.md).