The present invention provides termination for transmission line structures propagating common mode signals. Common mode signals typically represent noise in systems wherein information is transmitted as differential mode signals. The present invention terminates the common mode signals in a dynamically matched termination that prevents or significantly reduces reflection of said common signals without interference with differential mode transmission lines or their normal operation. Application is shown for an unshielded, twisted pair transmission line as commonly used in telephony-based systems for both voice and broadband data communication. The methods for application of the present invention to systems with large numbers of conductors are also shown.