Configure SIP Trunk & Numbers

Setting up SIP trunks and phone numbers in the Comcent Call Center web app is straightforward. Here’s a quick video guide to get started.

Following is text version of the video guide.

In this guide, we’ll use Twilio as our SIP trunk provider. To begin, log in to the Comcent app and navigate to the SIP Trunks section. Click “Create New SIP Trunk” and name it “Twilio.” There are two main steps to configure SIP trunks with Twilio:

1. Configuring SIP trunks for Outbound calls

Log in to the Twilio console and navigate to the Trunks menu, as shown below. If you don’t see “Elastic SIP Trunking” in the side menu, you may need to pin it from the Explore Products section. On the Trunks page, you’ll find a list of any existing trunks. For this guide, we’ll create a new SIP trunk. Click the “Create New SIP Trunk” button, provide a name, and proceed with the trunk creation.

Navigate to the Termination menu, which is used to configure outbound calls. As shown below, add the unique subdomain for the termination SIP URL. Add the termination SIP URL in the SIP proxy address field on the Comcent SIP trunk creation page. With this SIP URL configured we are telling Comcent to send outbound calls the this URL.

From now on, all outbound calls from Comcent will be routed through the Twilio SIP trunk. But how does twilio know that the call is coming from a genuine Comcent server? This is where authentication comes into play.

Authentication methods

There are two methods to authenticate outbound calls:

A. IP Access Control Lists method

You can whitelist the Comcent server’s IP address.

Navigate to the Trunks page in the Twilio console and click on “IP Access Control Lists” to create a new access control list. Provide a friendly name for the list, and then enter the IP address 34.194.224.59/32 (This is Comcent SIP Server’s IP Address). This step will allow only communication from Comcent’s IP addresses to communicate with Twilio.

B. Credentials List method

Another method to authenticate outbound calls is by creating a credential list. Here we use username and password as a way to authenticate outbound calls. To do this, click on “Credentials Lists” in the Trunks section of the Twilio console. Create a username and password, and then add them to the credential list.

In Comcent SIP Trunk setup page, enable “Provide Outbound Credentials” option. Copy the same username and password you just created from Twilio into the appropriate fields in Comcent’s SIP Trunk creation page.

Save the Twilio configurations.

2. Configuring SIP trunks for Inbound calls

Navigate to the origination page in the Twilio console and add the domain name of the Comcent SIP server as the origination and the URL is sip:sip-server.comcent.io. This configuration allows Twilio to route inbound calls correctly to the Comcent server.

How do we know inbound calls are coming from a genuine Twilio server? This is where inbound authentication comes into play. We will whitelist the Twilio IP address as an authentication mechanism. 54.172.60.0/30 is Twilio server’s IP address. Let’s add it to the inbound IPs field on the Comcent SIP trunk creation page, as illustrated below, and then click Create button to create the SIP trunk.

Configure Phone numbers in the Comcent Call Center web app

We need at least one phone number configured to make and receive calls. Navigate to the Active Numbers section in the Twilio console, where you will find the purchased numbers. If you need to acquire a new number, you can do so by clicking the “Buy a Number” button, as shown below. For our case, we will be using the existing numbers.

Configure the number to work with the SIP trunk by clicking on the number, selecting the SIP trunk for the Configur with option, and then choose the SIP trunk called Demo you created in the previous steps from the next dropdown. Finally, click “Save” to apply the changes.

Navigate to the numbers page in the Comcent application and create a new number. Enter your purchased phone number from Twilio in E.164 format. From the dropdown, select the previously created SIP trunk. Enter the regex pattern to restrict outbound calls.

To configure how Comcent handles inbound calls, use the flow diagram. For our case, we have added dial node and configured it with an agent’s username as shown in the image below. With this configuration, inbound calls will be forwarded to the agent.

This completes the configuration of SIP Trunk and Numbers in the Comcent application.

To test, navigate to the Twilio console origination page and click on “Make a Test Call.” If everything is set up correctly, you will receive the call in the Comcent application.

Congratulations! You have successfully configured Comcent to work with Twilio. You can follow similar steps to connect Comcent with other SIP trunk providers.

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