DTMF Signaling on four-wire switched 56 Kbps Lines

摘要

Dual tone multi-frequency (DTMF) address signaling on four-wire switched 56 kilobits per second (Kbps) service lines is obtained by determining the proper byte boundary information. An iterative learning process is used with an existing digital switching network having a call progress indication capability. The learning process steps through each possible byte alignment until the call progress protocol indicates that a proper byte alignment has been achieved. Once a paper byte alignment has been determined, that byte alignment information is retained for subsequent use, thus avoiding the need to repeat the learning process.