AT&T on Friday launched an international plan for the iPhone, offering users who travel overseas frequently some relief from expensive roaming charges that have led to at least one lawsuit against iPhone maker Apple.

The plan gives iPhone users 50 Mbytes of data per month to browse the Web, check e-mail, and access other information in 29 countries, including Canada, China, Mexico, and areas throughout Europe and Asia. The new Data Global Plan is available for $60 a month, which is in addition to the domestic voice and data plan iPhone users buy initially to activate the phone. AT&T is the exclusive service provider for the iPhone.

The international plan cannot be bought separately, and has to be an add-on to the domestic plan. Customers who exceed the 50 Mbye maximum will pay an additional $0.005 per Kbyte in those countries covered by the plan. In other areas, subscribers will pay double the amount, or $0.010/Kbyte.

For iPhone subscribers who can get by with a smaller data plan, AT&T is offering 20 Mbytes for $25 a month. The same rate applies for exceeding the amount in designated countries. Outside those areas, the data usage rate jumps to $0.0195/Kbyte.

AT&T has a Website that lists the countries where service is available.

Expensive roaming charges were the impetus behind a class-action lawsuit filed in New York in August. Herbert Kliegerman filed his suit in state court after he received a $2,000 bill due to data roaming charges incurred while in Mexico for a week.

The suit claims Apple misled consumers about potential roaming charges, and wants the court to order Apple to disclose codes to unlock the phone upon request.