Patent ID: 6295313
Filing Date: 2001-09-25
Classification: H04L,H04M,H04N,Y02D

Abstract:
A modem control method applicable to a V.34 facsimile modem which operates in compliance with the ITU Recommendation T.30 ANNEX-F for a calling modem and an answering modem mutually connected via a communication line, the modem control method comprising:receiving a signal having a specific frequency inserted in a communication control procedure;comparing a level of the received specific frequency signal with a predetermined value;carrying out communications at a lower transmission rate when the comparing indicates that the level of the received signal is lower than the predetermined value,wherein the specific frequency signal includes probing signals L1 and L2 in a pre-communication procedure transmitted from the calling modem, andwherein both first setting of a transmission rate and second setting that determines whether communications between the calling modem and the answering modem are permitted be at different transmission rates are carried out by assigning the first and second settings to different bits in a MPh signal of a control channel, the MPh signal being used for exchanging operating parameters between the calling and answering modems and for determining a transmission rate of signals transmitted through a primary channel that follows the control channel, andwherein, when a current transmission rate of the control channel is 2400 bps, the MPh signal requests the calling modem to communicate at a transmission rate of 1200 bps.