Telephonic communications – Telephone line or system combined with diverse electrical... – Having transmission of a digital message signal over a...
Patent
1990-07-10
1993-03-30
Dwyer, James L.
Telephonic communications
Telephone line or system combined with diverse electrical...
Having transmission of a digital message signal over a...
379102, H04M 1100
Patent
active
051990717
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of matching operation modes of Data circuit terminating equipments (DCE) such as modems (modulators/demodulators) for connection of terminals to a telephone line, i.e., operation forms determined by a communication speed, a coding format, a synchronizing mode, etc., on both the calling and answering sides of the telephone line.
BACKGROUND OF THE INVENTION
Digital data communication via telephone lines as analog circuits have become more prevalent, and modems for performing analog-to-digital and digital-to-analog conversion of signals between terminals and telephone lines have been used widely. To make matching with various signal formats and transmission formats, modems are required to have various operation modes. For example, an operation mode is determined dependent on setting conditions such as a standard specified in Recommendation from Consultative Committee of International Telegraph and Telephone (CCITT) V.21, V.22, V22bis, V.23,V.26bis, V.27ter or V.29, a communication speed given by 300, 1200, 2400, 4800, 7200 or 9600 bps (bits/second), a synchronizing mode given by synchronous or asynchronous mode, the presence or absence of echo protection, etc.
For carrying out data communication via telephone lines, it is essential to match operation modes of modems on both the calling and answering sides with each other. A conventional mode matching method has been practiced by confirming an operation mode of a modem at the other party in advance, and then (a) manually setting an operation mode of one's own modem or (b) replacing one's own modem with another one as required, in conformity with the operation mode of the opposite modem. However, such a conventional method is disadvantageous in requiring the intricate process to set an operation mode after exchanging information between the calling and answering sides prior to connection of a line, and to replace the existing modem with a new one when the setting cannot be completed. It is also difficult to be adaptable for many kinds of operation modes.
DISCLOSURE OF THE INVENTION
An object of the present invention is to reduce intricacy in matching operation data circuit terminating equipment (hereinafter called "DCE") such as modes of modems at the transmit and receive ends of a communication line as encountered in the prior art, and to automate the matching of operations modes.
When the answering side detects an extension specifying signal sent from the calling side, an operation mode of a DCE corresponding to the extension specifying signal is read out of conversion means to select the specified operation mode among a plurality of operation modes for DCE circuits equipped on the answering side for matching the operation mode of the answering side DCE with that on the calling side.
The answering side DCE has a function of detecting a push-button dial signal serving as the extension specifying signal, and a function of providing the plurality of operation modes for the DCE and optionally changing the operation mode upon an instruction from an answering side terminal. The answering side terminal has means for determining the correlation between the extension specifying signal from the calling side and the operation mode of the DCE. A calling terminal sets a call using a telephone number which contains the extension specifying signal of the dial-in service (direct inward dialing service) corresponding to the operation mode of the DCE and the answering side terminal has means for converting the extension specifying signal to the corresponding operation mode.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a system to which a matching method of the present invention is applied;
FIG. 2 shows a relay system for dial-in lines;
FIG. 3 shows a number applying method for dial-in lines;
FIG. 4 is a block diagram showing the configuration of hardware of a terminal and a modem for implementing the method of the present invention;
FIG. 5 is a functional block diagram of the modem;
FIG. 6 i
REFERENCES:
patent: 4788657 (1988-11-01), Douglas et al.
patent: 4916607 (1990-04-01), Teraichi et al.
patent: 4935955 (1990-06-01), Neudorfer
patent: 4939767 (1990-07-01), Saito et al.
Abe Ken-ichi
Kaji Kenzou
Kaneuchi Masumi
Kurashina Kenji
Sumiyoshi Kikuo
Chan Wing F.
Dwyer James L.
NTT Data Communications Systems Corporation
Ohkura Electric Co. Ltd.
Texas Instruments Japan Ltd.
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