When a payphone customer makes a long-distance call with an access code or 1-800 number issued by a long-distance communications carrier, the customer pays the carrier (which completes that call), but not the payphone operator (which connects that call to the carrier in the first place). The long-distance carrier is required to compensate the payphone operator for the customer's call. The payphone operator can sue the long-distance carrier for these 'dial-around' calls. Many payphone operators assign their dial-around claims to billing and collection firms called 'aggregators,' and the aggregators can bring suit on their behalf. The present litigation involves a group of aggregators who have taken claim assignments from approximately 1,400 payphone operators. Each payphone operator signed an Assignment and Power of Attorney Agreement (Agreement) in which the payphone operator 'assigns, transfers and sets over to [the aggregator] for purposes of collection all rights, title and interest of the [payphone operator] in the [payphone operator's] claims, demands or causes of action. After signing the agreements, Ps filed lawsuits in federal court seeking dial-around compensation from Sprint, AT&T, and other long-distance carriers. Ds moved to dismiss the claims, arguing that the aggregators lack standing to sue under Article III of the Constitution. The District Court initially agreed to dismiss, but changed its mind in light of a 'long line of cases and legal treatises that recognize a well-established principle that assignees for collection purposes are entitled to bring suit where [as here] the assignments transfer absolute title to the claims.' A divided panel of the Court of Appeals for the District of Columbia Circuit agreed that the aggregators have standing to sue, but held that the relevant statutes do not create a private right of action. The Supreme Court vacated the judgment and remanded the case for reconsideration, and on remand, the Court of Appeals affirmed the orders of the District Court, allowing the litigation to go forward. Ds appealed.