By Marina Lopes NEW YORK (Reuters) – T-Mobile U.S. Inc and Univision Communications Inc announced on Thursday they will launch a wireless service targeted at Hispanic Americans, the latest innovative marketing attempt by the fourth-largest mobile carrier in the United States. Univision Mobile, which will run on T-Mobile’s network, will be available at certain Walmart stores and other independent dealers on May 19 and includes unlimited international texting to select Latin American countries. The service also gives customers 100 minutes they can use to call Mexico and seven other Latin American countries.