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Open source PBX: Risk or value?

Open source IP PBX systems like Asterisk have benefits and risks. Learn what they are and assess your readiness for the IP PBX implementation in this tip from Gary Audin.

If it is free, does it have value? Free for business application, the open source PBX also has risks, costs and...

limitations. I took a look at this phenomenon in my webcast, "Asterisk -- Is 'free' good enough?"

Open source development is really a community effort, not a specific vendor's solution. This broadens the number of those producing the code but also diffuses the focus for support of the open source code.

This tip is focused on the concept of the open source PBX, along with its advantages and risks. There are several other open source PBXs besides Asterisk. Those will be explored in a subsequent tip. Open source means that the source code is shared freely for use by anyone as they see fit. Improvements and fixes will be distributed without restriction. The development of source code is performed by a community of volunteers that is open for anyone to participate. A good reference is "Open Source Decision Making and Implementation" from Business Communications Review , May 2005,

Open source vs. proprietary solutions

The following is a comparison between the open source and proprietary PBX solutions:

Open source Proprietary
No license fee Seat or site license
Change as you wish Strict limitation on code
Community of programmers Vendor's core team
No dedicated support from developers Vendor offers support
Documentation from community Professionally written documentation
Software releases driven by community and needs Software releases driven by customer input and vendor investment
No vendor lock-in Vendor lock-in

The advantages of open source community development are faster development cycles, fixes that are more rapidly developed and distributed, and a lack of restrictions by a proprietary vendor looking for profit. The proponents of open source point to the "project maintainers" who monitor the code production, thereby reducing the security risks. Large-scale commercializers of the open source code contribute to quality assurance. Vendors are now surfacing that will provide the open source implementation support.

There are many ways to keep abreast of the continuing development of the open source code. There are mailing lists, real-time chat networks, new user forums, Web sites specific to each open source PBX, free downloads, developer blogs, and conferences. Another good article also from Business Communications Review is "Open Source Telephony: The Devil's (Still) in the Details," May 2006.

Pluses and minuses

The plus side of the open source debate has these elements:

  • Opening up multivendor possibilities
  • Many system integrators gearing up to support open source VoIP
  • Interoperability among the products that is higher than that found with proprietary solutions
  • Many choices with reusable code
  • Many vendors that have entered the market with multiple products

Not everything that appears good is worth pursuing. There are counterarguments to the open source PBX solution. All this innovation by a large community of developers can and does cause confusion. Users of open source code will have to integrate many pieces or hire someone to do it for them (at a cost). A major issue for those looking for medium to large implementations is predicting the capacity before implementation. Many users had to implement and then determine what capacity they actually achieved. Other points on the minus side are:

  • Procuring an open source PBX will require modification to most enterprises' bid solicitation and contracting procedures.
  • The internal staff will require training, and the staff may have to be expanded.
  • Poorly controlled developers can create odd and ill-conceived software.
  • Low-cost devices to connect to the open source PBX may really mean cheap.
  • Echo-cancellation technology can be a problem.
  • DTMF support can be in five different implementations. The phone call will be connected, but IVR access to voicemail or call centers may not work.
  • Advice and best practices

    The advice I would give to prospective open source implementers is to be cautious. The two main issues are software maturity and commercial versions with vendor support. An enterprise has to look at open source if only to ensure that there are good reasons not to go down the open source path. The best practices and considerations for moving to an open source PBX are as follows:

  • Ensure that the upper IT or telecom management is committed to the implementation, not just an experiment.
  • Limit the number of operating systems used. One open source PBX has its own version of Linux.
  • Internet RFC standards compliance does not equal universal operation.
  • If more than one vendor's products are to be mixed together, make the vendors demonstrate interoperability.
  • Don't let the techies make the open source decision. They should be recommenders, not decision makers.
  • If proceeding, test, test, then test. Do not make any assumptions.
  • There are and will be successes with open source PBX implementations. Be cautious. Your organization may not be able to support the PBX, and the open source PBX may not scale to the size you eventually want to reach.

    About the author:
    Gary Audin has more than 40 years of computer, communications and security experience. He has planned, designed, specified, implemented and operated data, LAN and telephone networks. These have included local area, national and international networks as well as VoIP and IP convergent networks in the U.S., Canada, Europe, Australia and Asia.

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