FAX-telephone interface circuit

• US 5,499,287 A
• Filed: 12/13/1994
• Issued: 03/12/1996
• Est. Priority Date: 11/12/1992
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Campbell, Bob, Graf, John D., Nayak, Nandini, Gowan, Curtis R., Beck, Alan R.
• Primary Examiner(s): Hopsass, Jeffery A.
• Assistant Examiner(s): TSANG, FAN S
• Application Number:
  US08/357,049
• Time in Patent Office: 455 Days
• Field of Search: 379/67, 379/88, 379/89, 379/100, 379/201, 379/372, 379/373, 379/374, 379/375
• US Class Current: 379/442
• CPC Class Codes: H04M 1/82 Line monitoring circuits for call progress or status discrimination for detecting caller identity H04M1/573
• CPC Class Codes: H04N 1/32704 Establishing a communication with one of a facsimile and another telecommunication apparatus sharing a single line
• CPC Class Codes: H04N 1/32708 Telephone
• CPC Class Codes: H04N 1/32713 Data transmission device, e.g. switched network of teleprinters for the distribution of text-based information transceiver
• CPC Class Codes: H04N 1/32717 a calling tone, e.g. CI
• CPC Class Codes: H04N 1/32719 a facsimile calling signal, e.g. CNG
• CPC Class Codes: H04N 1/32723 speech signals
• CPC Class Codes: H04N 1/32726 signals other than facsimile protocol signals, e.g. DTMF signals
• CPC Class Codes: H04N 1/32728 an off-hook condition
• CPC Class Codes: H04N 1/32732 within a predetermined time
• CPC Class Codes: H04N 1/32741 Generating ringing or calling signals or tones
• CPC Class Codes: H04N 1/3275 Giving priority to one of the apparatus
• CPC Class Codes: H04N 1/32758 Sending a voice message other than from a telephone answering machine

Abstract

An improved telephone interface box which interfaces an incoming telephone line to either a modem or a telephone handset is disclosed. The choice of connection is made by a controller that answers incoming calls and determines if the call is to be directed to the modem or the telephone line. The controller determines the destination of the incoming call by detecting tones on the telephone line or by examining the response of the caller to a voice prompt. If the controller determines that the incoming call is to be directed to the telephone handset, the controller generates a ring signal having substantially the same cadence as that detected on the incoming line and sends that ring signal to the telephone handset. If the handset goes off-hook during the time the controller is making its determination as to the correct destination for the incoming call, the controller suspends its operation until the handset is placed on-hook or a predetermined time interval elapses. The controller also allows the handset to assert priority over an existing connection by rapidly depressing the off-hook switch on the handset.

Claims

1. An apparatus for connecting a modem and a telephone handset to a telephone line, said apparatus comprising:

means for coupling said apparatus to said telephone line;

means for coupling said apparatus to said modem;

means for coupling said apparatus to said telephone handset;

switch means, responsive to a switch control signal, for connecting either said telephone handset or said modem to said telephone line;

means for detecting a ring signal on said telephone line;

off-hook detecting means for detecting if said telephone handset is off-hook, said off-hook condition being indicated by an off-hook signal generated by said off-hook detecting means; and

control means, responsive to said ring signal detecting means, for determining if a telephone call received on said telephone line is to be directed to said handset or said modem and for generating said switch control signal, wherein said control means further comprises means for detecting a sequence of off-hook signal pulses and wherein said control means terminates any connection between said telephone line and said modem and causes said switch means to couple said telephone handset to said telephone line when said sequence of off-hook signal pulses is detected thereby allowing said telephone handset to be used to initiate a telephone call on said telephone line.

2. The apparatus of claim 1 wherein said control means further comprises:

means for detecting said off-hook signal; and

means for interrupting said determination of whether said received telephone call is to be directed to said handset or said modem when said control means detects said off-hook signal.

3. An apparatus for connecting a modem and a telephone handset to a telephone line, said apparatus comprising:

means for coupling said apparatus to said telephone line;

means for coupling said apparatus to said modem;

means for coupling said apparatus to said telephone handset;

switch means, responsive to a switch control signal, for connecting either said telephone handset or said modem to said telephone line;

means for detecting a ring signal on said telephone line, said ring detecting means further comprising means for detecting the cadence of said ring signal;

ring signal generating means for generating and coupling a ring signal to said telephone handset; and

control means, responsive to said ring signal detecting means, for determining if a telephone call received on said telephone line is to be directed to said telephone handset or said modem and for generating said switch control signal, said control means further comprising means for causing said ring signal generating means to generate and couple a ring signal to said telephone handset having a cadence the same as that detected by said ring signal detecting means if said control means determines that said telephone call is to be directed to said telephone handset.