An interface, such as a cashless interface, is interposed between a communication port of a gaming machine and one or more external devices and systems, such as a slot machine interface board and a slot management system. The cashless interface may further communicate with a financial system, such as via a controller and a gateway. The cashless interface may be used to facilitate the transfer of funds between a player's e-wallet associated with the financial system and a gaming machine, such as initiated via a player via their mobile communication device.