George Ou beleives the next frontier is VoIP and Open Source coming together.Excerpts from the excellent article with edits and my comments added:
As the commoditization and open sourcing of operating systems and applications continue to disrupt the software companies, telephony vendors have so far enjoyed a relative calm in the closed and proprietary phone systems market with substantial profit margins. That could now all be turned on its head with the proliferation of open source VoIP and PBX software. There are now a handful of these open source telephony platforms such as OpenPBX and Pingtel, but one of the most interesting is Asterisk, which even has its own communication protocol IAX in place of SIP for unified signaling and data transport.
Asterisk’s IAX has all the attractive characteristics of SIP yet it plays nice with NAT and firewalls due to the fact that it uses a single UDP port for signaling and voice transmission. SIP, on the other hand, uses one port for signaling and another for voice, which makes it difficult to handle in NAT and firewall devices. Another benefit of IAX is its trunking capability, multiple voice channels can share a single IP datagram (think of this as the enclosure for voice packets). This is no small feat, since the overhead of an IP datagram can be anywhere from two to five times bigger than the actual voice data itself while traversing Frame Relay or VPN tunnels! If the IP header can be shared, it can mean the difference between supporting 19 simultaneous G.729 voice channels using SIP or 55 simultaneous G.729 channels when using IAX where 512 kbps of a Frame Relay link is allocated for voice traffic.
Asterisk is not just another VoIP server,but is an extremely flexible communications platform that can serve as a VoIP Signaling Server, a Media Gateway (allows IP telephony to interface with analog phones, fax machines, or PSTN lines), a traditional analog or TDM-based PBX phone system, voice mail, IVR, Unified Messaging, and too many other things to list! The only catch (but diminishing),is it boils down to ease of use and having a person who is really good with Linux. However, you can always hire a consultant to implement the system for you on an hourly basis or go to one of the many companies selling turnkey systems . With all these developments, Asterisk is on the verge of critical mass to explode on to the VoIP scene – which will revolutionize the IP telephony market.My Take :VoIP market is witnessing a major revolution - with explosive groeth- at the same time, the services are getting fully commoditized. With open source solutions now becoming available, VoIP should witness more growth with more niche players joining the industry and this would help in bringing stability and embracing standards in the industry. Indeed a significant development.