As with the original iPhone, AT&T will be the only provider of the 3G model—introduced to much fanfare by Steve Jobs and company the other day—in the United States. While the new iPhone delivers considerably more features for less cash up front ($199 with a two-year contract for the 8GB edition, $299 for 16GB), it'll cost more to use on a monthly basis.

So instead of $20 per month for Internet access on AT&T's pokey EDGE data network, you'll need to pay $30 a month with a voice plan of $39.99 or higher to access the carrier's much faster 3G data network.

That's not the only change in the way AT&T plans to handle the iPhone with the new model either.

With the 3G iPhone, there's doesn't appear to be a pay-as-go option, apparently making the two-year sign up a prerequisite for use. Also, you'll no longer be able to activate your iPhone at home through iTunes. Rather, you'll have to have this done for you while you're in the store.

In addition to altering the way it does business with customers, AT&T and Apple have changed the way they do business with each other. Their new agreement is closer in spirit to the partnerships AT&T enjoys with its other cell phone and smartphone partners.

So, the companies have eliminated the revenue-sharing model of the original iPhone, under which AT&T shared a portion of monthly service revenue with Apple. Rather, with the 3G iPhone, Apple gets its cash from the sale of the device itself.

Apparently, this new agreement is the reason why AT&T can afford to subsidize the cost of the new iPhone to the point where it goes for hundreds of dollars less than the original model did when it first went on sale last June. AT&T anticipates the ability to subsidize the iPhone will help drive increased sales volumes and revenues.

Today, less than 20 percent of AT&T's postpaid subscribers have integrated devices capable of voice, Web and data applications. Based on the carrier's experience, average monthly revenues per (ARPU) for iPhone subscribers is nearly twice that of the company's overall subscriber base.

So, by getting more people to buy an iPhone by making it more attractive and cost effective to consumers, AT&T should be able to get more folks using its data services, therefore growing overall ARPU and growing revenue in the long run.