Each week Ross Rubin contributes Switched On, a column about consumer technology.

In the short history of smartphones, handsets carrying all but one of the major operating systems have been available to multiple U.S. carriers. That exception is iOS, for which the iPhone has been the only model. Of course, the iPhone's close cousin, the iPod touch, is available regardless of carrier (or service fees, for that matter), and has sometimes been referred to as "the iPhone for Verizon users." Ultimately, though, it's not. While the iPod touch provides access to a dizzying array of functionality that will likely expand this fall, its lack of an integrated cellular radio and attendant voice calling features means that it cannot assume that primary role in one's digital life in the same way that many smartphones have.

For this reason, the notion of a Verizon iPhone remains one of the hottest rumors in the industry, with many assuming that it would cause a fundamental shift in the competitive landscape. But there are many reasons that a Verizon iPhone may take years to arrive -- if it ever does -- and may not create nearly the disruption that it has on AT&T.

Competition. When the iPhone first appeared, carriers rushed to field an array of touchscreen feature phones that resembled the iPhone's form, but couldn't match its functionality. As the iPhone 4 came to market, Sprint and Verizon both launched Android devices with massive 4.3-inch screens; these are being complemented by Samsung's Galaxy S Android devices at all major carriers. Some may consider Android a "poor man's iOS" while others may see it as an open or superior alternative. But it's clear that even Android will encounter more competition in the next year as RIM continues to revamp the BlackBerry OS and Microsoft introduces Windows Phone 7.

Renewed exclusivity. One reason that people suspect a Verizon iPhone might appear in 2012 is the evidence that Apple and AT&T signed a five-year exclusivity agreement. Why did Apple agree to such a long period, knowing that it would open the door to competitors at Verizon? It's reasonable to assume that the terms of the deal simply favored Apple financially. That holds open the door that AT&T might be willing to continue to invest in keeping the iPhone exclusive and try to renew the contract, particularly since Verizon's switch to LTE will open the door to more handsets, particularly ones that can roam globally.

Pricing.
AT&T's decision to eliminate unlimited data plans in favor of two pricing tiers at $15 and $25 per month penalized its most active users, but lowered the monthly bills for many more. Verizon has indicated that it too will move to tiered pricing. But if it maintains today's smartphone pricing, many AT&T customers might stick with the carrier for the less expensive tier offering. Of course, Verizon knows how to stimulate demand with pricing, as it's shown with its various smartphone buy one-get one promotions. Traditionally promotion-shy Apple, though, might not want to participate in such giveaways, however.

The next Switched On will delve more deply into certainly the most significant technical variable surrounding a Verizon iPhone: the multi-year transition to the LTE standard.


Ross Rubin is executive director of industry analysis for consumer technology at market research and analysis firm The NPD Group. Views expressed in Switched On are his own.