When you have a customer with an IP PBX or other SIP-enable equipment, the below configuration will allow options in redirecting calls in the event the SIP Trunk fails which could be the direct result of the customer losing their Internet access or having an equipment failure. The concept involves using the functionality of the Hosted Domain associated with the SIP Trunk in order to accomplish the fail-over. This failover configuration will require 2 DIDs, one assigned to a routing user and one assigned to the SIP trunk. The DID assigned to the routing user will be the published DID. The other DID will not be known by the public.

Step-by-step guide

  1. Browse to the SIP Trunk Domain.

2. Click Add User

Here we will add a user to the domain associated with the SIP Trunk. You can name the user anything you want. We will in this example name it "Routing User." When adding the user, "Department" is not necessary, an "Email Address" is required although this is not an actual user, select "Basic User" for the "User's Scope," no "Caller ID" necessary, do not enable "Voicemail," do not "Add Phone Extension," and "Password" is a required field.

3. Assign DIDs

Next, we will assign DIDs. Navigate to the Inventory in the associated SIP Trunk Domain. Here you will assign the first DID, this DID will be the published main DID, you will assign this DID to the routing user just added, Routing User Extension 499.

Note: If you need to purchase DIDs prior to this step, then you will need to go to Manage DIDs, purchase the DIDs, and route them into the associated SIP Trunk Domain and then return to this step.

For this example, we are going to assign 469-342-2144 as the published DID. We are going to assign this number to the Routing User Extension 499. As below, click on the number and assign it to the user. This treatment of the published DID will send all calls to the routing user which we will use to redirect calls in the event of a failure.

Now we will assign the second DID to the SIP Trunk. You will need to navigate to the Reseller Account Level by clicking on View All Domains.

Then click on Inventory as the Reseller Account Level.

Next, we will assign the second or unpublished DID to the SIP Trunk. The number we are assigning in this example is 469-342-2143.

4. Setup Failover Setting

Now, we will use the Answering Rules of the Routing User to redirect calls in the event of a failure. Navigate to the Answering Rules inside the Routing User Extension 499, to get there click Domains, click on the domain associated with the SIP Trunk, click on the Routing User, and lastly click on the tab for Answering Rules.

Important Note:

Ring Time - you need to set a ring time here on this routing user that is longer than the ring time on your IP PBX that is on the customer premise. If your ring time on your IP PBX is 30 second then this ring time needs to be set to 40 seconds or higher. This allows full functionality of your IP PBX on the customer premise and keeps the Routing User from interfering with any calls.

Next, you will need to edit the Default Active Answering Rule.

Below you will see that we have set the ALWAYS FORWARD to the unpublished DID that we assigned to the SIP Trunk, 469-342-2143. Second, we use the WHEN UNANSWERED Option of the Routing User to redirect calls in the event of a failure. In this example, I have set the when unanswered to go to my mobile phone number. You can set the when unanswered to go to any number or any extension. Therefore, you could send the calls to an Auto Attendant, Voicemail, Call Queue, etc. Now in the event of the SIP Trunk or Equipment failing, the When Unanswered option works immediately, it DOES NOT wait out the Ring Time. The system knows that if the Always option is not available to automatically trigger the When Unanswered immediately and redirect calls as set.

Lastly, in this example, the DID 469-342-2144 is the published main number. When this DID is called the calls flow through the Routing User and are ALWAYS FORWARDED the unpublished DID which is assigned to the SIP Trunk which will allow the calls to flow to the customer premise IP PBX or other SIP enable equipment. In the event, the Internet Access to the customers' location fails or there is a failure in any of the customer premise equipment then the Hosted Functionality of the Domain associated with the SIP Trunk through the configuration of the Routing User's Answering Rules will redirect the calls.