did not adopt a single national database but rather required each company to maintain its own do-not-call database. The FCC's initial do-not-call list regulations were ineffective at proactively stopping unsolicited calls because the consumer had to make a do-not-call request for each telemarketer. In 2003, the Federal Trade Commission — not the FCC and not the agency entrusted with the TCPA — established the National Do Not Call Registry and implemented regulations prohibiting commercial telemarketers from making unsolicited sales calls to persons who did not wish to receive them. After being challenged in court by the telemarketing industry, the National Do Not Call Registry received Congressional ratification in the speedy enactment of Do-Not-Call Implementation Act. In 2013, the Philadelphia Federal Appeals Court held that consent to receive calls from collectors, banks, or telemarketers to consumers' cell phones may be revoked by the consumer. The CAN-SPAM Act made a minor amendment to the TCPA to explicitly apply the TCPA to calls and faxes originating from outside the U.S. The portions of the TCPA related to unsolicited advertising faxes were amended by the Junk Fax Prevention Act of 2005. Unusual statutory provision Though the TCPA is a federal statute, suits brought by consumers against violators are frequently filed in state courts. The TCPA is unusual in that the language creating a private right of action led to conflicting views on whether the federal courts had federal question subject matter jurisdiction. The TCPA provides in relevant part: "A person or entity may, if otherwise permitted by the laws or rules of court of a State, bring in an appropriate court of that State. ..." Prior to January 2012, there was a circuit split among the federal appeals courts on the issue of whether federal courts have federal question, diversity jurisdiction (individually or under the Class Action Fairness Act of 2005), or whether the state courts have exclusive jurisdiction. In 2012, the Supreme Court decided Mims v. Arrow Fin. Servs., LLC, which resolved the circuit split by concluding that "The TCPA's permissive grant of jurisdiction to state courts does not deprive the U.S. district courts of federal-question jurisdiction over private TCPA suits." Major court cases The TCPA's constitutionality was challenged by telemarketers soon after it was enacted. Two cases, Moser v. FCC, 46 F.3d 970 (9th Cir. 1995) cert. denied, 515 U.S. 1161 (1995) and Destination Ventures Ltd. v. FCC, 46 F.3d 54 (9th