PBX and SIP Trunk using PortSIP SBC

This topic describes how to set up PortSIP SBC for interworking between the generic SIP trunk and PortSIP PBX.

1 Topology of the Interoperability Environment

The interoperability testing between SBC and a generic SIP Trunk with PortSIP PBX was done using the following topology setup:

  • Enterprise deployed with PortSIP PBX in its private network for enhanced communication within the Enterprise.

  • Enterprise wishes to offer its employees enterprise-voice capabilities and to connect the Enterprise to the PSTN network using a SIP Trunking service.

  • PortSIP SBC is implemented to interconnect between the Enterprise LAN and the SIP Trunk.

    • Session: Real-time voice session using the IP-based Session Initiation Protocol (SIP).

    • Border: IP-to-IP network border between PortSIP PBX network in the Enterprise LAN and SIP Trunk located in the public network. The figure below illustrates this interoperability topology:

2 Configuring PortSIP PBX

Please follow the below topics to install and configure the PBX:

3 Configuring PortSIP SBC

Please follow the below topics to install and configure the SBC:

4 Adding SIP trunk to the PortSIP PBX

Assuming the trunk information is below:

  • SIP Trunk in the internet

  • SIP Trunk IP is, port 5060

  • SIP Trunk transport is UDP

  • SIP Trunk is IP authorization mode or register authorization mode

To add the trunk to the PBX:

  1. Sign in to the PortSIP PBX Web Portal by "System Admin" credentials, and click the menu "Call Manager > Trunks".

  2. Click the arrow button to choose the IP-based or Register-based trunk type to add.

  3. Enter a friendly name for this trunk, and fill in the "Host Domain or IP" with SIP trunk IP and "Port" with 5060. If the trunk port is not 5060, please enter the actually port.

  4. Fill the "Outbound Proxy Server" with the SBC private IP in case is, and fill the "Outbound Proxy Server port" with the SBC port 5069 , by default, the SBC uses the port 5069 on TCP to receive the SIP message from PBX.

  5. Select the TCP transport and click the "Next" button.

  6. If the trunk is "Register based" type, enter the "Authorization Name" and "Password" here, it gave by your trunk service provider.

  7. Turn on the "Trunk is located in same LAN with PBX" option.

  8. Turn off the "Rewrite the host IP of Via header by public IP when sending the request to trunk" option and click the "Next" button.

  9. Since the trunk is added by the "System Admin", the "System Admin" will need to choose one or more tenants to allow them access to this trunk. Please refer to the "Add the Trunk by System Admin" section of Trunk Management.

In summary, just add the SBC likes add a normal trunk, fill the trunk's IP or domain to the "Host Domain or IP", and fill the SBC's IP and port to the "Outbound Proxy Server", set the transport to TCP since the PBX use TCP to communicate with the SBC, and the call flow is:

extension <---> PBX <---> SBC <---> SIP Trunk

Now you completed the SBC trunk settings, you can follow this guide to create the inbound and outbound rules as the normal trunk.

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