In the past year we've seen increased demand for VoIP, most notably in the consumer peer-to-peer market. With Skype leading the way, peer-to-peer VoIP using the Internet has attracted major industry players such as Microsoft, Google, Yahoo and AOL. EBay's purchase of Skype and Microsoft's pushing instant messaging voice and the next-generation Windows Vista operating system will no doubt elevate peer-to-peer VoIP to a mainstream Internet application.

These consumer VoIP applications cannot be truly classified as telephony because most lack a set of robust standard features and the ability to connect to services such as 911. The use of Internet peer-to-peer VoIP to avoid carrier toll charges is the paramount driving force enticing users to the technology.

With IM becoming an important means of communication in the corporate environment, can IM-enabled VoIP be just over the horizon? If so, what will become of the corporate PBX?

There are two lines of thought on this subject. In the first case, transition to a hybrid PBX/IP-PBX environment is recommended to ease migration to VoIP. In the second case, a total "greenfield" switch to an all IP-PBX environment is recommended. Variations of these recommendations exist when taking into consideration handset upgrade/replacement and wireless access.

The reality of the marketplace may have created a third alternative based upon software virtualization/Web services technology and the potential of widespread corporate adoption of standards-based IM and peer-to-peer desktop operating system services. Today, several vendors market a peer-to-peer desktop equivalent to a PBX. This technology has not been widely adopted but proves the feasibility of the concept.

The "virtual PBX" is an extrapolation of this concept using Session Initiation Protocol (SIP)-based IM or equivalent handset services at the desktop, coupled with a corporate virtualized software application that provides a full set of telephony services - features, directory assistance, policy, administration, management and most importantly, on-net/off-net least-expensive routing access. If this sounds like the old concept of Centrex or the new concept of a softswitch, it is the natural evolution of both expanded to accept the next-generation software technologies.