METHOD OF MATCHING OPERATION MODE OF A MODEM

WIPO Patent Application WO/1990/003701

A1

A method of matching the operation mode of a modem that connects a digital terminal equipment to an analog telephone circuit at both the calling side and the called side of the analog telephone circuit. When the communication is to be carried out in a synchronized mode, first, the invention provides a matching method wherein a digital terminal equipment connected to an end of the telephone circuit is operated, the digital terminal equipment having means which, depending on an operation instruction, designates the stored operation mode of the opponent's modem for the modem, and wherein the modem analyzes the instruction to select operation mode reference data and sets the operation mode of the modem to a predetermined mode. Second, according to the invention, mode instruction signals by DTMF are transmitted and received between digital terminal equipment connected to both ends of the telephone circuit using multi-frequency DTMF codes for selection used in the telephone circuits, such that operation modes of the two modem devices are automatically brought into agreement with each other. That is, even when the initial operation modes are different between the calling side and the called side, a desired operation mode is set on the calling side. After the called side is off-hooked in response to the calling signal, (1) the operation mode instruction signal is sent from the calling side to the called side using DTMF codes, and when this mode can be set on the called side, this mode is set and a response sound is returned back to the calling side. On the called side, furthermore, when there is not set the mode instructed by the calling side, an operation mode that can be operated is sent from the called side to the calling side using DTMF codes. When the mode can be set on the calling side, a code of the mode is sent again from the calling side to the called side to match the two operation modes, and (2) an operation mode instruction signal is sent from the called side to the calling side using DTMF codes in order to attain matching by the same method as that of (1) above.

SUMIYOSHI KIKUO (JP)
ABE KENICHI (JP)
KANEUCHI MASUMI (JP)
KURASHINA KENJI (JP)
KAJI KENZOU (JP)

PCT/JP1989/000976

April 05, 1990

September 27, 1989

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TEXAS INSTRUMENTS JAPAN (JP)
NTT DATA COMMUNICAT SYST CORP (JP)
OKURA DENKI CO LTD (JP)

H04L29/06; H04M11/06; (IPC1-7): H04M11/00; H04M11/06

JPS6229344A	1987-02-07
JPS61128679A	1986-06-16
JPS6331257A	1988-02-09
JPS61281664A	1986-12-12
JPS635648A	1988-01-11
JPS61276451A	1986-12-06

See also references of EP 0390931A4

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