A digital tandem channel unit installable in an intermediate central office of a digital carrier telephone network maintains the digital format of the T1 traffic in the course of a DS0 tandem cross-connect, so as to eliminates the possibility of corruption of voice/data traffic, as may occur in a conventional...http://www.google.com.au/patents/US5337306?utm_source=gb-gplus-sharePatent US5337306 - Digital tandem channel unit interface for telecommunications network
