When Congress passed the TCPA in 1991, it delegated the do-not-call rules to the FCC. Congress suggested that the FCC's do-not-call regulations "may require the establishment and operation of a single national database." The FCC 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.