AT&T is introducing new mobile data usage price plans that, it says, are all about making smartphone packages more affordable for more people. (See AT&T Unveils Mobile Data Plans.)

But the real deal about the operator's new monthly mobile data packages -- announced very late Tuesday -- is that its $30-per-month, unlimited data usage plan currently on offer to its smartphone users will no longer be available to new customers from June 7.

Instead, new subscribers hooking up to AT&T's wireless networks from that date will be limited to a certain level of data usage as part of their monthly fees, after which they will have to pay for any additional bytes downloaded.

The move, which comes only days before the expected unveiling of the latest iPhone at the Apple developers' conference and in the midst of a consumer clamor for the iPad, looks like the latest attempt by AT&T to control the volumes of data flooding across its mobile network, which buckled under the weight of increasing non-voice application usage last year. (See Bye, Bye Unlimited iPad Data Plan, International Sales Push iPad Over 2M Mark, iPhone: Could Multitasking Increase 3G Woes?, and Is AT&T Ready for the 3G iPad?)

The operator is also investing an additional $2 billion this year to bolster its mobile infrastructure and avoid the outages it suffered in New York City and San Francisco. (See AT&T Plots Widescale HSPA+ Rollout , AT&T to Spend $2B More on Wireless in 2010, and AT&T Mobile Boss: NYC & San Fran Are 'Underperforming'.)

The new prices certainly lower the entry level, with the cheapest package, called DataPlus, starting at $15 per month. That deal includes 200 Mbytes of data -- enough, says AT&T, to send or receive 1,000 emails or view 400 Web pages. Currently, 65 percent of the operator's smartphone users use less than 200 Mbytes of data per month, according to AT&T. An extra 200 Mbytes of data can be bought for an additional $15.

That means anyone on that tariff who uses 201 Mbytes in any given billing month will be charged $30. AT&T says it will text customers when they are approaching their data limits. In addition, customers, if they're using an iPhone or other "select devices," can monitor their data usage using the AT&T myWireless application.

The $15 data offer means a customer can get a voice and data package for $55 per month (before taxes and other variable fees). Currently, the entry level price is $70 per month.

For those who want more data, a 2-Gbyte package, called DataPro, is available for $25 per month. Those who go over that limit can get an extra 1 Gbyte for $10. AT&T says 98 percent of its current smartphone customers use less than 2 Gbytes of data per month. DataPro customers will also be able to use their mobile devices as wireless modems to connect other devices, such as laptops, to the AT&T mobile network for an extra $20 per month.

The shift away from unlimited mobile data usage had been expected, and was hinted at during a keynote session at this year's Mobile World Congress in Barcelona involving AT&T's John Stankey, president of the carrier's Operations group.

But as industry analysts have suggested, this should only be the start of a broader strategy to fully realize the financial potential of mobile data applications. (See Optimize or Monetize Mobile Network Investments?)

— Ray Le Maistre, International Managing Editor, Light Reading