All the signals were there and now it’s actually happening. AT&T is the first of what will certainly be a flurry of operators that will start phasing out those yummy ‘all you can eat’ packages for mobile data.

AT&T will no longer offer new customers its unlimited Internet data (UD) plan for smart phones and iPads. This move coincides with the release of a new iPhone 4 and version iOS4 of its operating system that will allow some form of multitasking. This is predicted to dramatically increase data usage via iPhones and iPads.  No doubt, part of AT&T’s thinking is the hope of easing congestion on its network by charging the people who use the most data more.

However, the approach could confuse customers unfamiliar with how much data it takes to watch a YouTube video or fire up a favorite application. AT&T will warn subscribers when they near their package limit and provide options for continuation of service, no doubt at a premium. This means that AT&T will need to monitor everyone’s usage in real-time so the impact on the back-office could be as dramatic as the effect on the network was when UD packages were first released.

Current subscribers will be able to keep their $30 per month unlimited plans, even if they renew their contracts, but starting June 7, new customers will have to choose one of two new data plans for all smart phones, including iPhones and BlackBerries.

New subscribers who use little data will pay slightly less every month than they do now, while heavy users will definitely attract higher bills.

Analysts, renowned for stating the bleeding obvious, expect other mobile operators to follow suit. No surprise considering Sprint has already hinted at it.

In markets that did not offer unlimited data packages the increases of data usage were nowhere near as dramatic as those that did. The question now is, by capping data volumes will there be a subsequent negative effect on the growth of data traffic. The introduction of the iPhone and unlimited data plans were concurrent. Apple was either very brilliant in foreseeing this and convincing AT&T to introduce UD plans or they were just plain lucky.

Looking back, if AT&T knew the effect the iPhone would have they may not have offered UD packages with it. What would have happened if they didn’t? The iPhone, and the flurry of ‘wannabes1’ it created, may not have been as successful,but on the other hand, data usage and revenues may not have advanced as rapidly as they have. Catch 22?

1. Imitators or ‘want to be(s)’