Configuration of a SIP Trunk


  • Set up an IP PBX accessible from everywhere in the SU campus
  • Configure a SIP trunk in the PBX to receive and make calls
  • Produce IP PBX and SIP trunk documentation useful for future projects in CCENT


A PBX is the traditional system that enables telephones with extension numbers in an enterprise environment to be connected among themselves and to the outside public network including mobile phones networks. An IP-PBX provides for the same audio capabilities and adds video and instant messaging communications through IP packets exchanges over the enterprise internal data network. Its capabilities can be extended over the enterprise managed intranet (that connects different separate locations). An IP-PBX can also be connected to the traditional PSTN (Public Switched Telephone Network). Physically, an IP-PBX is either a dedicated device (hardware) or a software that can be installed on a server.

Asterisk is an example of a free open source communication platform (including a software based IP PBX) sponsored by Digium, and it is the platform used for the VoIP CCENT project. Asterisk has been installed and configured to accommodate 2 extensions in each of the work areas in CCENT and one extra extension for each student. This project also aims to configure a firewall between the PBX and its clients. Communications (IP packets) from and to the IP PBX server need are inspected and filtered for security reasons. Giving that the IP PBX server should be accessible from both internal and external networks, a DMZ has to be configured (Demilitary Zone, less secure than the internal network).

For testing purposes, this project will implement a small local network, a server and a couple of laptops inside the CCENT. The server hosted the configured Asterisk PBX. Softphone applications were installed on the laptops and the firewall is being configured to allow communications. The whole purpose at this point, is to verify the consistency of the different configurations before moving to the next stage. Once everything is tested and working the IP PBX will be deployed in the production environment of the CCENT. Finally, SIP trunks will be configure to allow access to the PSTN from the lab.


Lino Samklu

Lab supervisor: Jose Bejar

Faculty supervisor: Prof. Bahram Attaie