To use iPhone, you’ll need to sign up for a 2-year service agreement. Plans start at $59.99 and include Visual Voicemail and Unlimited Data — email and web — and 200 SMS text messages (you can add more text messages for a little more a month). You can browse the Internet and send emails as often as you like without being charged extra.
Existing AT&T Customers
If you’re an existing AT&T (formerly Cingular) wireless customer on a qualifying rate plan, just add an iPhone Data Plan. (This may replace your current data plan. Some voice plans, including TDMA, may not qualify. Call AT&T Customer Service at 1-800-331-0500 or visit an AT&T store to see if your plan qualifies.) iPhone Data Plans give you Visual Voicemail, SMS Text Messaging bundles, and Unlimited Data, which includes both email and web.
Check AT&T coverage in your area.
AT&T is the exclusive carrier for iPhone in the United States — which means you’ll gain access to the country’s largest digital voice and data network.
Source:http://www.apple.com
