If you're considering an open-source phone system for your large business, Stephane Alnet says you should ask yourself an important question: are you sure you want to do that? "You probably don't," said Alnet, CEO of Urbana IL-based telecom consultancy CarrierClass.net, making a presentation at IT360, a technology conference in Toronto. Speaking specifically about enterprise deployments of Asterisk, the most popular open-source IP phone system, Alnet pointed out that the platform might not be ready for large-scale projects.Asterisk wasn't designed for big businesses, he said. It supports 100 to 150 users no problem, but 5,000? "That's a different story."He provided advice for large firms that insist on trying Asterisk - businesses that believe open-source software is inherently better than proprietary software, regardless of the potential management headaches associated with the open-source route. A SIP proxy server will have to be part of the rollout in order to support more than just 100 or so users, Alnet said. As well, central phone configuration systems are few and far between: CarrierClass.net had to build its own. Asterisk deployers must resign themselves to more than the usual amount of do-it-yourself.Plug tab A into slot BA roomful of DIYers attended Kevin Fleming's presentation on Asterisk at the conference. Director of software technologies at Huntsville AL-based Digium Inc., the firm behind the Asterisk phenomenon, he described some of the functions on tap to make Asterisk more enterprise-friendly. The Asterisk Network Edge project will let the IP-PBX control network gatekeepers, allowing them to address firewall traversal problems. Digium worked with Morganville NJ-based Ranch Networks Inc. for that, Fleming said. He added that Digium is also working with San Mateo CA-based Vyatta Inc. to integrate Asterisk and Vyatta's open-source routing/firewall platform for network-edge control.Upcoming call-bridging software could make Asterisk more palatable for contact centres, Fleming said. The technology would let managers listen in on calls for quality control, and it would support in-call announcements, which would interest service providers.In the future, Asterisk will be able to support hundreds of simultaneous calls, and a new core infrastructure will support voice mail stores separate from call servers, Fleming said. Companies can configure Asterisk that way now, but message-waiting lights on phones won't work properly without some tweaking, he explained.Beyond the next release - v.1.6, which may or may not be available by the end of the year (Digium's release schedule seems based on a simple concept: "release when the product is ready"), Asterisk will provide call-server clustering and failover, which enterprises need to ensure the phone system doesn't go offline, Fleming said.Fleming also said the Digium team is trying to figure out how to provide that functionality without redesigning the entire platform. After all, Asterisk is meant for small businesses. "It's actually a very difficult problem to solve."IP-PBX acrobaticsRepresentatives of Asterisk user groups are solving other problems, although their efforts don't address enterprise issues. Simon Ditner from the Toronto Asterisk User Group (TAUG) demonstrated an application he built that lets people play Zork - the text-based video game from the 1970s - through the telephone. It's built on the Asterisk IVR and took just 48 hours to create, he said.Clod Patry from the Asterisk Montreal User Group (AMUG) demonstrated a conference-call manager that lets an administrator bridge callers, and end sessions via a Web interface. He also repeated his "voicechanger" demo, which he presented at a Toronto technology conference last year as well. This application simply raises or lowers the caller's voice pitch, giving it an eerily low or high tone. "It could be useful for making prank calls," Patry said. "I have too much fun with that application."Although these programs have little to do with business, their existence is encouraging. As Ditner said, easy application development is a hallmark of open-source telephony; companies could build their own unique software on the Asterisk platform. For his projects, "it became less and less about Asterisk, and more and more about the limits of my own imagination," he said.In many respects, discussions about Asterisk now are similar to the discussions people were having about Linux, the open-source operating system, five years ago. Back then, the industry wondered if Linux would ever be ready for business use. Now, that question applies to Asterisk. In both cases, the query glosses over covert implementations occurring in corners of enterprises, where future-curious IT departments are poking open-source systems to see what they can do, and whether they have a future in large companies.This underground movement, coinciding with new functions, could raise Asterisk from a small-office/ hobby system to a genuine enterprise telephony contender."It's not there yet," said Alnet from CarrierClass. "I hope to come back next year and tell you it is."Time for a new OSI chartIn his discussion of enterprise Asterisk deployments, Alnet said it's time to extend the OSI chart by a few more layers. Beyond the usual 1 through 7, IT managers should also consider Layer 0 - real-world physical infrastructure, such as electricity, backup generators, emergency resource locators, heating, cooling, and building access. Layer 8 deals with operations, such as IT team training, skills updates, and end-user considerations like executive training. This is important for Asterisk implementations. "It's very easy to get to three nines" of system uptime, Alnet said. "To get to five nines, the big difference is operations."Layer 9 has to do with internal company politics. Are there government regulations that the company must meet, and that open-source telephony might break? Is the firm comfortable using open-source software, from a legal perspective? Some aren't.Layer 10 is a matter of "religion," Alnet said: some firms are gung-ho for open source. Others are philosophically opposed to it. IT leaders should know their corporation's stance before forging ahead with Asterisk.