If you wanted any more proof that data is the future for wireless network operators, just look at the recent shift in so-called unlimited plans. Verizon Wireless, Sprint, AT&T, T-Mobile and, this week, Alltel have all unveiled unlimited voice plans for about 100 bucks a month.

Yet the pattern with wireless data seems to be going in the opposite direction. Verizon Wireless has officially set caps on its previously unlimited plans for EV-DO laptop access. $60 for 5 GB of data with per-MB charges applying thereafter. And there are plenty of rumors that AT&T plans to do the same thing on its unlimited data phone plans. The underlying logic appears to be that what was once the most valuable service, voice, is now a commodity that can be sold cheap or unregulated. And what was once a fringe service like Internet access has now become the exact opposite of a commodity: it’s a service in which demand is over taking supply and the use of which must be restricted.

Good for the wireless operators. They’ve been trying to fill up their new data networks for years, and it seems we’ve finally reached a point where those billions of dollars of investment are now justified. But have we really reached that point? After some recent conversations with Mike Schabel, a former scientist with Bell Labs and now manager of Alcatel-Lucent Ventures’ Aware project, I’m not sure that the networks are filling up -- at least not the way we think they are.

Schabel started the Aware project as a security initiative to identify threats to the performance and integrity of the wireless radio network. But what Schabel found was that “practically everything” was a threat to the network. The reason: wireless applications today were built with close attention to the bandwidth limitations of the network but not necessarily to their overall resource limitations. Many wireless apps focus heavily on signaling. The BlackBerry is the perfect example. It may download an insignificant amount of data in a day, but the device and the BlackBerry enterprise server will signal each other thousands of times in a day regardless of whether there is a message waiting. And every time a signal is sent out an IP address is assigned, a channel is opened and shared airtime is allocated.

Push e-mail isn’t the only culprit. In fact, the wireless network was tailor-made for these kind of hyper-signaling applications. Real-time location-based services, presence-based apps, instant messaging, mobile VPNs -- they all depend on lifeline to the network. And by virtue of the fact they are “always on” they are literally always connected to the network.

In his analysis of network usage across several operators, Schabel found that these signal-heavy apps are the ones that are taking a toll on the 3G channel, not capacity-hungry apps, which would appear to go against common sense. But Schabel found that while the peer-to-peer services, video streaming services like Slingbox and file downloads definitely accounted for main portion of the packets traversing the network, signaling accounted for the most airtime and ultimately contributed the service disruptions we’ve started to see across the world. By his calculations, a laptop left unmolested in a hotel room with a live VPN connection running takes a much greater toll on the network than someone watching a 30-minute sitcom on Slingbox.

Yet the trend among mobile operators is to set pricing and policies based on overall data consumed, which is partly fair but it’s only partly the problem. Capacity is shared on the wireless network, unlike on the home broadband network, and operators are definitely right to ensure that a few capacity hogs don’t ruin everyone else’s experience. But setting data caps won’t prevent millions of new BlackBerrys sending the same of “Have I got any mail? How about now?” signals bouncing about, and the operators will be back where they started.

So what’s the answer? Charge for airtime? Charge using some arcane algorithm that takes total resource usage into account? Charge for each individual service? I doubt any of those solutions will work. And I certainly don’t envy the operators as they try to sort this muddle out.

Contact me at kfitchard@telephonyonline.com