The U.S. Supreme Court is set to provide a crucial definition related to the Telephone Consumer Protection Act that could refine the scope of the law.

On Thursday, the nation’s high court granted Facebook Inc.’s petition for certiorari in a case that asks the justices to provide guidance on what exactly qualifies as an automatic telephone dialing system (ATDS). The law prohibits companies from using an ATDS to contact consumers without their consent, but courts’ definition of the device has differed.