In theory, an open source IP telephony system will increase the demand for IP telephony, create better interoperability between IP phone systems and drive down the cost of IP telephony by putting price pressure on the traditional phone system vendors. An open source model for IP telephony might yield these results at some time in the distant future, but it will have no such effect in the short term, for a number of reasons.

The major reason is that, for most companies, the phone system is the most important communication tool the organization has. Some software developers or network managers might tinker with open source software, but no CIO will rest the fate of the company's most important customer-facing tool on an unproven technology. Open source IP telephony systems lack the necessary features and management tools to make the technology a viable alternative to current phone systems.

Additionally, today's phone system buyers are primarily traditional voice managers or data networking managers, not application developers. Voice and data managers want an IP telephony system that can replace their TDM systems, not IP telephony software that can be deployed, modified and tweaked. This is one reason the dominant voice and data vendors such as Avaya, Nortel and Cisco carry the lion's share of the IP telephony market. Any open source solution will not easily integrate into a traditional vendor environment, adding to the difficulty of engineering a quality IP telephony system.

Supporters of open source IP telephony also say the technology will generate more interest in IP telephony. This is more myth than reality. There is already a tremendous amount of interest in IP telephony technology. A recent Yankee Group survey indicates that 78% of all U.S.-based companies have an interest in IP telephony.

The main deterrent to deploying IP telephony across the company today is quality of service and manageability issues, not infrastructure costs. The Yankee Group research shows that software and hardware costs total less than 20% of the cost of running a network. Better tools to manage the IP telephony ecosystem will drive down costs and drive up adoption faster than a new model for pricing the IP PBX platform. There are many third-party companies focused on providing management tools, which currently are being developed for the traditional vendors - meaning that an IP telephony system from Cisco, Nortel or Avaya will be more manageable than one from an open source vendor.