We are still remembering Steve Ballmer’s doubts about the iPhone’s appeal to business users, but AT&T apparently had enough reason to tailor specific voice and data plans just for this customer base: The plans do not directly compare to the firm’s other business plans, but are somewhat pricey nevertheless.

In addition to a business voice plan, which AT&T offers from $40 (450 included minutes) to $200 per month (with 6000 included) minutes, the enterprise data plans are priced from $45 (200 SMS, unlimited email and web data) to $65 per month (unlimited SMS and unlimited email and web data). Users signing up now are getting a $25 discount on these 2-year agreement plans until the end of this year.

For people travelling internationally, AT&T offers special plans: For an additional $25 month you can download up to 20 MB of data in 29 supported countries; $60 buys 50 MB. In regions outside these 29 countries, AT&T will still charge $0.019/KB, which translates into $19.97/MB. Given the fact that the standard average Google Map has a size of somewhere between 500 KB and 1 MB when downloaded onto the iPhone, users could be facing substantial additional data charges when using this service globally and outside of Google’s iPhone pages. AT&T also charges its customers $0.005/KB ($5.12/MB) within those 29 countries as soon as the 20 MB or 50 MB account is exhausted.

Of course, these charges shouldn’t be a sticker shock to Blackberry users, who are paying with AT&T at least $40 for a voice plan, between $20 and $45 for a basic data plan (5 - 50 MB of email and web data), between $65 and $135 for international data plans per month and between $5 and $20 for SMS capability.