Configuring Twilio Register Based Trunk
Before proceeding with the next steps, you need to purchase a DID on Twilio.
Create a SIP Trunk on the Twilio Platform
To create a new SIP trunk on the Twilio platform, follow these steps:
Sign in to your Twilio Console.
From the left-hand navigation bar, go to Elastic SIP Trunking
Alternatively, click the Elastic SIP Trunking icon in the left vertical navigation bar.
Navigate to Manage > Trunks.
Click Create new SIP Trunk.
Enter a friendly name for the trunk, then click Create.
Configure Trunk Termination
After creating the SIP trunk, leave all settings on the General page unchanged and proceed to the Termination section. This section defines where outbound calls from PortSIP PBX are sent to Twilio.
Step 1: Configure the Termination SIP URI
In the Termination section, enter a unique Termination SIP URI of your choice.
If the URI is displayed as Available (shown in green), it is valid and can be used.
❗Important Note the full Termination SIP URI (for example,
portsip-pbx.pstn.twilio.com). This value will be required later when configuring the SIP trunk in PortSIP PBX. Your URI must be unique and will differ from the example shown here.
Step 2: Configure Authentication (IP ACL)
Scroll down to the Authentication section.
Under IP Access Control Lists (IP ACLs), create a new ACL entry.
Add the public static IP address of your PortSIP PBX.
You can find this IP address on the PortSIP PBX Home page.
❗Best Practice IP-based authentication improves security by ensuring that only your PBX is allowed to send traffic to Twilio.
Step 3: Configure Credential List (Optional / Recommended)
In the Credential List section, create a username and password pair.
Save the credentials.
Click Create to save the Termination configuration.
Once completed, navigate to the Origination page to continue the Twilio trunk setup.
❗Note These credentials will also be used later when configuring the Twilio SIP trunk in PortSIP PBX.
Configure Trunk Origination
In the Origination section, you define how inbound calls from Twilio are routed to PortSIP PBX.
You will add one or more Origination SIP URIs that point to your PortSIP PBX.
❗Prerequisite Ensure your PortSIP PBX has a static public IP address or FQDN. This information is available on the PortSIP PBX Web Portal Home page.
Step 1: Add the Primary Origination URI (US1)
In the Origination section, locate the Origination SIP URI configuration.
Enter the SIP URI in the following format (replace with your own PBX IP or FQDN):
Set the following values:
Priority:
10Weight:
10
Click Add.
❗Explanation This configuration routes inbound SIP traffic from the Twilio US1 (Virginia) data center to your PortSIP PBX and restricts origination to that region.
Step 2: Add a Secondary Origination URI (US2 – Failover)
To provide regional redundancy, add a secondary Origination URI:
Click the plus (+) icon next to Origination URI.
Enter the following SIP URI (replace with your own PBX IP or FQDN):
Set the following values:
Priority:
20Weight:
10
Click Add.
Explanation This URI allows Twilio to route inbound calls from the US2 (Oregon) data center only if the primary US1 region is unable to deliver the call.
Expected Result
Inbound calls from Twilio will first attempt delivery via US1 (Virginia).
If US1 is unavailable, calls will automatically fail over to US2 (Oregon).
PortSIP PBX will receive inbound SIP traffic securely and predictably.
Assign DID Numbers to Your Elastic SIP Trunk
After creating the Elastic SIP Trunk, you must assign one or more DID numbers to it.
Follow these steps in the Twilio Console:
From the left-hand navigation menu, go to Phone Numbers > Manage > Active Numbers.
Click the phone number you want to assign to the SIP trunk.
On the number details page, locate the Voice Configuration section.
For Configure with, select SIP Trunk.
In the SIP Trunk drop-down list, choose the Elastic SIP Trunk you created earlier.
Click Save Configuration.
The selected DID number is now associated with your Elastic SIP Trunk. Inbound calls to this number will be routed through the SIP trunk to PortSIP PBX.
Configure the Twilio Register-Based Trunk in PortSIP PBX
The Twilio Register-Based Trunk corresponds to a Register-Based Trunk in PortSIP PBX.
You can configure this trunk at either of the following levels:
System Administrator level
The trunk can be shared with one or more tenants.
Tenant Administrator level
The trunk can be used only by that tenant and cannot be shared.
Step 1: Create the Register-Based Trunk
Sign in to the PortSIP PBX Web Portal as a System Administrator or Tenant Administrator.
From the left-hand navigation menu, go to Call Manager > Trunks.
Click Add, then select Register Based Trunk.
Step 2: Configure Basic Trunk Settings
Enter the following information:
Name Enter a friendly name for the trunk (for example,
Twilio-Reg-Trunk).Brand Select Twilio.
DID Pool (Tenant Admin level only) If you are configuring the trunk at the Tenant Administrator level, specify the Twilio DID numbers assigned to this tenant.
❗Important
The tenant can use only the DID numbers in its DID pool to:
Create inbound and outbound call rules
Configure outbound caller IDs for extensions
DID Pool Format Examples
Hostname or Address Enter the Twilio Trunk Termination URI created earlier, for example:
Click Next to continue.
Step 3: Configure Authentication Credentials
Enter the Authentication Name and Password that were created earlier in the Twilio Credential List.
Click Next.
Step 4: Configure Trunk Options
Need Registration Disable this option.
❗Twilio Elastic SIP Trunking does not accept SIP
REGISTERmessages.Max Concurrent Calls Defines the maximum number of simultaneous calls that PortSIP PBX can establish using this trunk.
Adjust this value according to your Twilio capacity and expected call volume.
Leave all other settings at their default values unless you have specific requirements.
Click Next to continue.
Step 5: Assign Tenants and DID Pool (System Admin level only)
❗Note This step is available only when configuring the trunk at the System Administrator level.
Assign the trunk to one or more tenants.
Provide Twilio DID numbers to each tenant using the DID Pool.
❗Important
Each DID can be assigned to only one tenant.
A tenant can use only the DID numbers in its DID pool to:
Create inbound and outbound call rules
Configure outbound caller IDs for extensions
DID Pool Format Examples
Click OK to save the configuration.
Expected Result
The trunk configuration is now complete.
Because Need Registration is disabled, the trunk status will always display as Online in the trunk list. This is expected and correct behavior for Twilio Elastic SIP Trunks.
Next Steps
Refer to Twilio Elastic SIP Trunking documentation for platform-specific details.
Proceed to Configuring inbound and outbound calls in PortSIP PBX.
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