With the gradual adoption of a unified client for internal use, users will benefit from using presence awareness with VOIP calling. As was the case with IM systems, however, administrators could face the prospect of having two integrated communications clients on user desktops -- a private one for internal use and a public one for free, peer-to-peer calling outside of the company. Eventually, clients for internal use may offer some degree of federation with public peering services such as Skype, Lazar predicts. But in the interim, peer-to-peer VOIP services are likely to continue gaining ground, particularly in organizations that haven't yet moved to IP telephony and in small and midsize businesses where the auditing and controls are less strict.

The benefits are just too compelling for users to ignore, says Stofega. "It's a cheap, simple application that gets the job done."