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Automatic modem identification system

  • US 4,215,243 A
  • Filed: 11/17/1978
  • Issued: 07/29/1980
  • Est. Priority Date: 11/17/1978
  • Status: Expired due to Term
First Claim
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1. The method of identifying a particular modem type from a plurality of modem types having common access to a port over a telephone line, wherein said modem types include at least a first and a second modem type, comprising the steps of:

  • (a) answering all the incoming calls received over said telephone line with an answering modem of said first type by transmitting for a first time period an answer mark carrier of a frequency which is not only unique to an answering modem of said first type but is also compatible with any other of said modem types;

    (b) monitoring said telephone line during said first time period to detect an originate mark carrier of a frequency unique to a calling modem of said first type;

    (c) maintaining communication with said calling modem of said first type upon the condition that the originate mark carrier detected within said first time period is of a frequency unique to a calling modem of said first type;

    (d) if no originate mark carrier is detected during said first time period, transmitting an answer mark of a frequency unique to an answering modem of said second type for a second time period;

    (e) monitoring said telephone line during said second time period to detect an originate mark carrier of a frequency unique to a calling modem of said second type; and

    (f) maintaining communication with said calling modem of said second type upon the condition that the originate mark carrier detected within said second time period is of a frequency unique to a calling modem of said second type.

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