Voice over IP took at least 10 years to effect some change in the traditional wireline telephony industry. Those 10 or more years were characterized by many fits and starts, with the concept of placing cheap long-distance calls — the longer the better, as some people used to say — over the Internet as the original ambitious — if ultimately flawed — proposition. That gave way to VoIP, an invention often criticized — initially justifiably, but ultimately unfairly — as lacking the quality ever to be taken seriously enough for broad commercial implementation.

Fast forward to 2005, and the gradual VoIP evolution is now a revolution, with the success of alternative service providers and the projects in place at traditional service providers as the proof. It may have taken at least 10 years for that to happen, but when it did, it was pretty impressive how the affordability, functionality and feature-richness of VoIP began to shake the foundation of an old industry that had been trying to squeeze every last drop of investment return out of its existing infrastructure concepts.

The wireless industry is not nearly as old as the wireline public network segment, so wireless might be forgiven for its disinterest in VoIP for now. However, VoIP isn't just a catalyst of change in the wireline market, but also in wireless, or at least in markets in which wireless carriers fancy themselves one of the viable competitive choices.

One of those markets is the residential market, where customers increasingly are cutting the cord on their residential wireline voice service. The other is the enterprise market, into which wireless carriers have been trying to make some headway for quite a while, with only sporadically positive results. VoIP is increasingly being accepted in both markets, as are wireless LANs, and sore are, increasingly and predictably, VoIP over WLANs.

It's not like anyone really expects that wireless carriers will rush to outfit their WANs with VoIP network elements and devices. Though the IP multimedia subsystem standard comes from the wireless realm and some wireless carriers have big plans for it, those plans don't generally involve VoIP. These carriers have spent the last 20 or so years improving and then proving voice quality on their existing networks — too much has been invested to outmode them just yet.

But, if wireless carriers are serious about becoming the phone inside the home and about becoming primary providers of enterprise services, it might be time to look at these markets in a different way. Especially in the enterprise, WLAN equipment vendors have started outfitting enterprises with VoIP in their WLAN coverage, and most of them wouldn't mind working with wireless carriers to create some kind of managed services that eventually could evolve into convergent cellular/Wi-Fi services when hybrid devices become available within the next year or so.

Some vendors say the wireless carriers are very hesitant, preferring instead an all-cellular-or-nothing approach to the enterprise. It may be easy to do so for now, with the business model for convergent services still unproven and the economics of hybrid device adoption still unclear. However, the wireless industry might not want to turn its back completely on VoIP. With its foot in the door, VoIP's next revolution probably will not take as long as the last one.