Patent Number: 6,480,596

Title: Direct inward-outward dialing trunk circuit

Abstract: A direct inward-outward dialing (DIOD) trunk circuit having a DIOD detecting/sending circuit connected to tip and ring terminals connected to a central office line and a primary coil of a transformer, for detecting a polarity of the voltage potential at the tip and ring terminals and the current flowing therethrough to determine reception of one of an incoming and outgoing telephone call, and a switch, controlled by a relay driver responsive to an interface circuit used for interfacing the DIOD trunk circuit with a switching circuit of a private branch exchange (PBX), for enabling the current to flow between the tip and ring terminals through the DIOD detecting/sending circuit via one of a low or high impedance path, wherein the low impedance path is used to establish a speech path between a central office line subscriber and a corresponding extension subscriber of the PBX.

Inventors: Min; Kyung-Hwa (Suwon, KR)

Assignee: SamSung Electronics Co., Ltd.

International Classification: H04M 7/00 (20060101); H04M 3/42 (20060101); H04M 003/38 (); H04M 003/00 (); H04M 007/00 ()

Expiration Date: 11/12/2019