... Hardware HDLC More efficient processing ability ISDN PRI signalling, with echo cancellation module The WSS-1E1/T1 supports Up to 1E1 ... HDLC, and Frame Relay data modes. The board drives both line-side and trunk-side interfaces, including call features.The card ... HDLC, and Frame Relay data modes. The board drives both line-side and trunk-side interfaces, including call features.The card ...