This is the third time that AT&T has added unlimited calling to Mexico in its different plans. The company previously brought it to World Connect Value and its subisidiary Cricket Wireless.
The mid-range HTC smartphone comes to the carrier's off-contract rate plans.
AT&T broadens its prepaid GoPhone service for certain tablets, including the Apple iPad 3 and Google Nexus 7.
The lower-end Lumia can be had for $99.99 without requiring the usual two-year contract.
The new plans range between $25 and $60 a month, and come after the company scrapped an older set of plans. Starting June 21, prepaid users can ride on the faster 4G LTE network.
AT&T is eliminating certain data plans available to its GoPhone prepaid customers. The company says new plans are coming.
The revamp means that 4G devices, including the iPhone, can now access data over the network instead of just relying on Wi-Fi.
The only catch? The phone is currently out of stock online, though Microsoft promises it will be available for Black Friday.
The new $200 Asus PadFone X Mini will become the first Intel-powered smartphone with LTE technology sold in the US.
The carrier's new smartphone plan, which costs $10 less per month than the previous offering, goes into effect October 7.