THREE-WAY CALLING AND CALL-WAITING ARRANGEMENTS FOR STEP-BY-STEP TELEPHONE SYSTEMS

• US 3,626,107 A
• Filed: 08/29/1969
• Issued: 12/07/1971
• Est. Priority Date: 08/29/1969
• Status: Expired due to Term

• Current Assignee: Stromberg-Carlson Corp.
• Original Assignee: George R. Bergquist, Loren K. Armstrong
• Inventors: Armstrong, Loren K., Bergquist, George R.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Brown, Thomas W.
• Application Number:
  US04/854,244
• Time in Patent Office: 830 Days
• Field of Search: 179/18BG,18BC,84B
• US Class Current: 379/204.01
• CPC Class Codes: H04Q 3/00 Selecting arrangements H04Q5/00 - H04Q11/00 take precedence

Abstract

Relay trees providing call-waiting and three-way calling services in step-by-step telephone switching systems, including interlock connections to insure unambiguous operation. The subscriber'"'"''"'"'s line makes two appearances in the linefinder and connector banks of the exchange, and is also connected to an auxiliary line circuit. The call-waiting and three-way calling circuits are individually assigned to the respective lines subscribing for them. Taken together, the circuits provide service substantially equivalent, and in respect of the conference capability, superior to a key-set telephone with two lines to the exchange and bidirectional trunk hunting.

Claims

1. A relay tree arrangement to provide three-way calling service for an individual subscriber'"'"''"'"'s line in a telephone switching system of the step-by-step type, said arrangement comprising an auxiliary line circuit, and a relay tree connected between the subscriber'"'"''"'"'s line, his regular line circuit, and said auxiliary line circuit, said relay tree including:

a. means normally connecting the subscriber'"'"''"'"'s line to his regular line circuit and enabling the placement and reception of calls through it in the ordinary way, b. seizure means for detecting when the subscriber is off hook, c. means for placing the regular line circuit on hold and connecting the subscriber'"'"''"'"'s line to said auxiliary line circuit in response to the subscriber'"'"''"'"'s going on hook momentarily after said seizure means has detected an off hook condition, d. means for connecting the inputs of the regular line circuit and said auxiliary line circuit in parallel in response to the subscriber'"'"''"'"'s once again going on hook momentarily, and e. means for disconnecting the subscriber'"'"''"'"'s line from said auxiliary line circuit in response to the subscriber'"'"''"'"'s going on hook momentarily a third time.

2. A relay tree arrangement to provide call-waiting service for an individual subscriber'"'"''"'"'s line in a telephone switching system of the step-by-step type, said arrangement comprising a relay tree connected between the subscriber'"'"''"'"'s line, his regular line circuit, and a separate terminal to which the regular line circuit is connected, said relay tree including:

a. means normally connecting the subscriber'"'"''"'"'s line to his regular line circuit and enabling the placement and reception of calls through it in the ordinary way, b. seizure means for detecting when the subscriber is off hook, c. means for detecting the appearance of a call incoming through the regular line circuit or at said separate terminal while the subscriber is off hook and connected to the other of the regular line circuit and said separate terminal, d. means responsive to said appearance detecting means for applying brief time spaced signals to the subscriber'"'"''"'"'s line to advise the subscriber of the appearance of the incoming call, and e. means for thereafter switching the subscriber'"'"''"'"'s line back and forth between the regular line circuit and said separate terminal in response to successive momentary openings of the subscriber'"'"''"'"'s hookswitch, and simultaneously placing on hold the disconnected one of the regular line circuit and said separate terminal.

3. A relay tree arrangement according to claim 2 including:

a. means for distinguishing between outgoing and incoming calls, and b. means controlled by said distinguishing means for releasing the regular line circuit on an outgoing call in response to the subscriber'"'"''"'"'s going on hook for a predetermined interval of greater duration than the momentary opening of the hookswitch required for response of said switching means.

4. A relay tree arrangement to provide three-way calling and call-waiting services for an individual subscriber'"'"''"'"'s line in a telephone switching system of the step-by-step type, said arrangement comprising a first portion providing three-way calling service, a second portion providing call-waiting service, electrical interlocks connecting said first and second portions to insure unambiguous operation, said first and second portions being connected in tandem between the subscriber'"'"''"'"'s line and the line circuit regularly assigned to it, said second portion being connected to a terminal in the connector bank of the system separate from the terminal to which the regular line circuit is connected, an auxiliary line circuit connected between said first portion and a terminal in the linefinder bank of the system separate from the terminal to which the regular line circuit is connected, said first portion including:

a. means normally connecting the subscriber'"'"''"'"'s line to his regular line circuit through said second portion and enabling the placement and reception of calls through it in the ordinary way, b. seizure means for detecting when the subscriber is off hook, c. means for placing the regular line circuit on hold and connecting the subscriber'"'"''"'"'s line to said auxiliary line circuit in response to the subscriber'"'"''"'"'s going on hook momentarily after said seizure means has detected an off hook condition, d. means for connecting the inputs of the regular line circuit and said auxiliary line circuit in parallel in response to the subscriber'"'"''"'"'s once again going on hook momentarily, and e. means for disconnecting the subscriber'"'"''"'"'s line from said auxiliary line circuit in response to the subscriber'"'"''"'"'s going on hook momentarily a third time, said second portion including;

f. means normally connecting the subscriber'"'"''"'"'s line from said first portion to his regular line circuit and enabling the placement and reception of calls through said second portion in the ordinary way, g. seizure means for detecting when the subscriber is off hook, h. means for detecting the appearance of a call incoming through the regular line circuit or at said separate terminal whilE the subscriber is off hook and connected to the other of the regular line circuit and said separate terminal, i. means responsive to said appearance detecting means for applying brief time spaced signals to the subscriber'"'"''"'"'s line to advise the subscriber of the appearance of the incoming call, and j. means for thereafter switching the subscriber'"'"''"'"'s line back and forth between the regular line circuit and said separate terminal in response to successive momentary openings of the subscriber'"'"''"'"'s hookswitch, and simultaneously placing on hold the disconnected one of the regular line circuit and said separate terminal, said electrical interlocks including;

k. means responsive to said appearance detecting means of said second portion for inhibiting the operation of said means of subparagraphs (c), (d), and (e) of said first portion during times when two calls are underway through said second portion, and l. means responsive to the means of subparagraph (c) of said first portion to insure that both the regular connector terminal and said separate connector terminal are marked busy from the initiation of a three-way call until its termination.