Quick search by citation:

4 U.S. Code § 117 - Sourcing rules

(a) Treatment of Charges for Mobile Telecommunications Services.—
Notwithstanding the law of any State or political subdivision of any State, mobile telecommunications services provided in a taxing jurisdiction to a customer, the charges for which are billed by or for the customer’s home service provider, shall be deemed to be provided by the customer’s home service provider.
(b) Jurisdiction.—
All charges for mobile telecommunications services that are deemed to be provided by the customer’s home service provider under sections 116 through 126 of this title are authorized to be subjected to tax, charge, or fee by the taxing jurisdictions whose territorial limits encompass the customer’s place of primary use, regardless of where the mobile telecommunication services originate, terminate, or pass through, and no other taxing jurisdiction may impose taxes, charges, or fees on charges for such mobile telecommunications services.
Statutory Notes and Related Subsidiaries
Effective Date; Application of Amendment

Section effective July 28, 2000, and applicable only to customer bills issued after the first day of the first month beginning more than 2 years after July 28, 2000, see section 3 of Pub. L. 106–252, set out as a note under section 116 of this title.