Digium Asterisk built on Session Initiation Protocol used in Switchvox IP PBXs
Private branch exchanges (PBXs) with open source telephony software may cost less than voice products from major manufacturers, but one industry observer warns companies who buy cheaper products will usually get fewer features.
Equipment manufacturers, resellers and end-users are buying open source software because they hear it will save them money, said Kevin Fleming, senior software engineer for Digium Inc. of Huntsville, Ala., which makes Asterisk, a Linux-based open source PBX operating system.
“To some degree, it’s completely irrelevant to the end user that it’s based on an open source product, other than the fact that they get a much more powerful system at a lower cost,” Fleming said. “They don’t necessarily care that it’s open source, they just go to the vendor and say, ‘This is what I want to do,’ and the vendor says, ‘Okay, we can do that for $4,000,’ and they go, ‘Wow. Okay. When can I have it?’”
Asterisk includes telephony services such as voicemail, conferencing, three-way calling and caller ID. It includes a central switching core, four application programming interfaces for telephony applications, hardware interfaces, file format handling and codecs. Version 1.2, which was released last November, supports the Distributed Universal Number Discovery protocol and supports more session-initiation protocol (SIP) features than previous versions.
SIP, which originated as a signaling protocol, allows telephony and conferencing devices from different vendors to work together, and support for open standards is one reason users choose open sources telephony, said Joshua Stephens, chief executive officer of Switchvox Inc., a San Diego-based maker of Internet Protocol telephony equipment based on Asterisk.
“Since Asterisk is built on top of SIP, and other open standards, it works with other people’s products, and you don’t have to worry about, ‘Did they do it this way or did they do it that way?’” Stephens said. “It removes a lot of the barriers that would otherwise be there with proprietary software.”
But just because a PBX supports SIP does not mean it will work with advanced features from other manufacturers, said Zeus Kerravala, vice-president for enterprise infrastructure at the Boston-based Yankee Group.
“More and more companies are embedding instant messaging features, Web conferencing, audio conferencing, different collaborative features,” Kerravala said. “It’s not just the ability to make the call.”
He added users who buy open source to save money may miss out on these advanced features, and may end up paying more to support the products.
“In general, you don’t get what you don’t pay for,” he said. “For the buyer, it may look attractive from an initial acquisition standpoint, but take a look a a five to seven to 10-year total cost of ownership, when you include hiring people, retaining people, training them.”
Kerravala said products from major manufacturers may be more expensive, but there are more technicians trained on these products.
“Even if you need a consultant to come and help you, you can pick up the Yellow Pages and find a bunch of Avaya-certified, Nortel-certified and Cisco-certified people, but to find anybody who knows Asterisk — that can be a lot more challenging.”
But open source allows more customization, and telephony products from major manufacturers may not have the features users want, Stephens said.
“You can fix things that are important to you and maybe not important to the company that manufactured it,” he said.
Switchvox manufactures IP PBXs and IP phones for small to mid-sized firms. The company had used open source in some of its other products, including Internet kiosks. Company officials wanted to build products that would allow users to establish their own calling rules, voicemail and e-mail, and to add new users from a Web interface.
“We come from a long line of working with open source,” Stephens said. “A lot of the people that we appeal to have PBXs. A lot of them decide, ‘Hey, I want to use voice over IP at some level,’ and their existing PBX doesn’t do it. They either use it so they can have remote workers working from home, and they want to take their phone with them, or they want to use voice over IP between PBXs at different locations so that employees at one location can just use extension dialling to get to the other location without having to pay any extra bills.”