Patent ID: 8879691

Claim:
A method of testing metallic integrity in a dry 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 dry transmission line via a dry digital subscriber line device serving the subscriber, the sealing line current provided from a sealing current source coupled to the dry transmission line via a low pass filter, the sealing current source and the low pass filter located in a remote digital subscriber line access multiplexer (DSLAM); supervising the provided sealing line current between the digital subscriber line device and a subscriber's premises for determining the metallic integrity and a connectivity of the dry transmission line, and for determining whether a leakage current is occurring; and measuring a loop resistance of the dry digital subscriber line based on the provided sealing line current to determine the connectivity of the dry transmission line.