A system, method, and computer readable medium for a metallic test method in a digital subscriber line system in which a subscriber's voice service has been switched from plain old telephony service to an inband digital subscriber line data stream characterized in that a direct current loop current used for plain old telephony service is replicated for testing, comprising, providing a sealing line current to a transmission line via a digital subscriber line device serving the subscriber and supervising the provided sealing line current between the digital subscriber line device and a subscriber's premises for determining a connectivity therebetween.