AT&T is offering the iPhone as part of its business program. Subscribers must have a voice plan and of the new Enterprise Data Plans for the iPhone. The data plans are broken down by the number of SMS messages subscribers can send, with 200 messages for $45, 1,500 at $55 and unlimited prices at $65 per month. Similar to the consumer data plans, Visual Voicemail and unlimited domestic data usage such as web browsing and email is included.

Subscribers traveling abroad may wish to opt for one of two Data Global Add-On plans: 20MB for $25 or $60 for 50MB. Note that either add-on will on cover 29 countries, including Canada, China, Germany and United Kingdom.

From now until March 31st, AT&T is offering a temporary discount as an incentive for upgrades and new subscribers. The offer: $25 credit per month, running through December 31st. Signing up for the iPhone Enterprise plan requires a new or renewed two-year contract. [via macNN]

In other iPhone news, Reuters this morning reported that Apple has begun discussions with Thailand’s Advance Info Service (AIS) to make it the iPhone’s network partner in the country.

“We are negotiating on details, including a revenue sharing standard. Apple needs a local operator to promote iPhone,” Prattana Leelapanang, assistant vice president for AIS’s wireless business marketing, told Reuters.

The news emerged not too long after reports last week claiming talks to launch the iPhone in China – went southbound. NTT DoCoMo and Softbank are also reported to be in talks with Apple to release the iPhone in Japan.