Three service plans will offer unlimited access to email and the web, 200 text messages and unlimited mobile-to-mobile talking.
The lowest price plan offers 450 minutes of talk time, along with 5,000 night and weekend minutes for $59.99 (£30). Plans with 900 and 1,350 minutes go for $79.99 (£40) and $99.99 (£50) respectively.
AT&T charges a $39.99 monthly fee for a regular phone plan without any data service and 450 minutes of talk time, putting the surcharge for the data service at $20 per month.
Each of the plans requires a two-year service agreement, and users will have to pay a $36 activation fee on top of the $499 or $599 price tag for either a 4GB or 8GB iPhone.
Apple revealed that users will be able to set up and activate their iPhones via iTunes. Apple co-founder and chief executive Steve Jobs promised that the set-up process would be familiar to Apple customers.
"There are tens of millions of people in the US who already know how to synchronise their iPods with iTunes, and synchronising their new iPhone with iTunes works the same way," he said.
The system will allow users to activate the device outside the store, but will also require every iPhone owner to have an iTunes Store account and access to a Mac or PC with iTunes installed.
The iPhone will go on sale on 29 June at 6pm local time. Apple plans to close its retail stores at 2pm in preparation for the launch. AT&T will close its stores at 4.30pm.
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