The Asterisk IP PBX and other open source software helps the city of Madera, Calif., build an VoIP network.
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Savings from all corners
The city's foray into open source began two years ago, when it brought on a new network manager, Paul Wheeler, specifically to shepherd through the VoIP conversion. Based on RFPs, the city was bracing itself to spend $350,000 to $400,000 to rip out a 25-year-old Mitel Networks PBX and replace it with a VoIP system.For the city, with its annual budget of $100 million and 500 employees, the new phone system would be a major expense.
Madera had set aside $140,000 for the project when Wheeler arrived. He wound up overhauling the entire city network, however, with open source applications that have expanded services at very little cost. "It turns out I gave them far more for that $140,000, and I never needed another penny," he says.
The Mitel PBX was so maxed out that the city was using small, supplemental Toshiba PBXs at branch sites and paid monthly fees for Centrex services to some offices. Small sites were tied into the citywide phone system via 50 off-premises extension (OPX) lines that cost $44 per month apiece. "I said [that] just turning off those OPXs is going to pay for this project," Wheeler says. The city also moved employees around and reconfigured offices, meaning a high demand for adds, changes and deletions (ACD) to the phone service. "The ACD cost was what I was really trying to drive to the floor," Wheeler says.
He has two reasons for wanting to try Digium's open source Asterisk IP PBX. First, Gov. Arnold Schwarzenegger recommended open source software as an inexpensive alternative to commercial wares. Second, the software was free and could be tested using a spare server. "The downside of testing it was zero," Wheeler says. "The only hardware cost I had was for Digium T-1 cards. The financial risk was negligible."
Asterisk comes with voice mail, conferencing and call distribution, for which some commercial systems charge extra. The gear proved itself on an internal test bed, and Wheeler targeted the public works department for the initial deployment of 50 extensions supported by Polycom Power-over-Ethernet (PoE) phones. He fronted the Mitel PBX with the Asterisk IP PBX and throughout the year switched over one phone at a time, so phone use was not broadly disrupted, he says.
Until the transition, the city was getting by with an eclectic collection of unmanaged switches. It replaced those with $40,000 worth of HP ProCurve PoE switches, chosen for their price and lifetime replacement guarantee, Wheeler says. City electricians handled the cabling requirements.
Open source all over
Previously, the city's WAN consisted of three T-1s: one to the Internet and two for data between city hall and the public works building, and between city hall and the building housing the police department and redevelopment agencies. A set of small Cisco routers stacked at these sites handled all the routing.
With the phone upgrade, the city expanded the WAN to tie in five more sites via T-1 links to the police department, city hall or public works building, each of which acts as a hub. The T-1s, bought through a California government consortium, cost $170 per month.
Each hub has its own Asterisk IP PBX that is connected to the public switched telephone network via an AT&T Primary Rate Interface line. Dual T-1s, one for VoIP, the other for data, connect each hub to the others. If a T-1 fails, voice and data combine on the remaining line. If one PBX fails, phone traffic it normally would handle is routed to the other two via new routers the city built based on Vyatta open source router software ($600 per router), standard Compaq x86 server hardware ($900) and a Sangoma Technologies T-1 card ($600), Wheeler says. He redeployed the Cisco routers to smaller sites.
With the phones and network overhauled, Wheeler has added more functions using a broad spectrum of open source software. These include Open VPN, Firewall Builder, TShark protocol analyzer, Apache Tomcat for Java development, PostgreSQL database, MapServer for creating maps and other images, Open NMS management platform, GLPI IT asset manager, Eclipse development platform, Aptare storage console and Snort intrusion detection.
"There was no open source here," he says. "I'm the open source guy."
Madera’s open source inventory
* Apache Tomcat for Java development
* Aptare storage console
* Digium Asterisk IP PBX
* Eclipse development platform
* Firewall Builder
* GLPI IT asset manager
* MapServer for creating maps and other images
* Open NMS management platform
* Open VPN
* PostgreSQL database
* Snort intrusion detection
* TShark protocol analyzer
* Vyatta routing software