How much do Apple customers use the iPhone for business? Apparently enough for AT&T to come up with a business rate plan for the smart phone. Of course, the plan comes with certain terms and conditions, and it’s twice as costly as the regular consumer plan, but AT&T definitely thinks it is worth it. iPhone has been a phenomenon ever since its launch, in the U.S. more than anywhere else in the world, and the mobile carrier wants to be a part of it more than anything these days.

The business plan offers pretty much the same features as for regular users, with data and voicemail services, but comes with a minimum two-year service agreement, and some pricier text message and voice plans than for regular consumers: $45 a month for 200 text messages, compared to just $20 for normal users, $55 a month for 1,500 text messages and $65 a month for unlimited texting.

At the same time, the corporations will have to sign every iPhone for a voice plan, which will be charged from $39,99 for 450 minutes to $199,99 for 6,000 minutes shared among users. AT&T even offers a $25 credit every month until the end of 2008 for those who will adopt their business plan by March 31, 2008.

Rumors on the Lotus Notes application for the iPhone IBM is about to launch have already been circulating, but nothing has been confirmed by IBM yet. The announcement is however expected to be made in the press conference on Tuesday, which will probably boost the iPhone use in business even more.

AT&T is the largest mobile carrier in the United States, with 63.7 million subscribers in the United States alone, and one of the biggest business communication service providers in the world. According to a 2007 press release, Randall Stephenson said: “Mobility is a major growth engine for AT&T. our launch with Apple of the breakthrough iPhone has quickly redefined customer expectations for their wireless experience, [and the] initial response was unprecedented.”