A telecommunications services provider’s roaming charges for when its Texas customers traveled to Mexico and placed or received calls that originated and terminated in Mexico, were not subject to Texas sales tax. The Mobile Telecommunications Sourcing Act (MTSA) provides a uniform national rule which assumes that all mobile telecommunications service charges are deemed to be provided by the customer’s home service provider and are subject to tax according to the place of primary use rule. However, the Act’s place of primary use rule does not apply when a wireless telecommunications subscriber travels to a foreign country and uses a wireless device to place or receive calls that originate and terminate in the foreign country because the subscriber is not using facilities located in the United States. The wireless telecommunications services at issue were provided in Mexico and Texas did not have the authority to impose tax (Decision, Hearing No. 100,587, Texas Comptroller of Public Accounts, June 4, 2010).