Circuitry for providing executive ringback in a PBX system

• US 3,956,595 A
• Filed: 10/03/1974
• Issued: 05/11/1976
• Est. Priority Date: 10/03/1974
• Status: Expired due to Term

• Current Assignee: AT&T, Inc.
• Original Assignee: Western Electric Company
• Inventors: Sobanski, Edward Walter
• Primary Examiner(s): Cooper, William C.
• Application Number:
  US05/511,753
• Time in Patent Office: 586 Days
• Field of Search: 179/18 B, 179/18 BG, 179/84 B
• US Class Current: 379/204.01
• CPC Class Codes: H04Q 3/625 Arrangements in the private branch exchange

Abstract

In a telephone switching system wherein a plurality of line circuits are terminated in station sets, the line circuits are interconnectable to a plurality of trunk circuits through a multistage switching network. A call originated by a calling party to a called party, engaged in a conversation with a third party, is completed at the conclusion of the conversation between the called party and the third party by ringing back the calling party provided the calling party is equipped with the class of service which permits executive ringback. The ringback feature is initiated by the calling party upon receipt of a busy tone by a flashing of his switchhook.

Claims

1. In a telephone switching system having a plurality of line circuits terminated in station sets, said line circuits being interconnectable to a plurality of trunk circuits through crosspoint connections in a multistage switching network, the invention comprising executive ringback circuitry for completing a connection between a calling station and a called station at the conclusion of a connection between said called station and a third party station, said executive ringback circuitry including

means for determining the class of service provided to said calling station,

means for detecting a busy condition of said called station,

means, activated by said class of service determining means and said busy condition detecting means, for seizing said executive ringback circuitry provided said calling station has a class of service permitting executive ringback,

means for enabling said executive ringback circuitry in response to a switchhook flash from said calling station, and

means, responsive to said switchhook flash enabling signal from said calling station, for holding said seizure of said executive ringback circuitry to maintain said crosspoint connections through said multistage switching network until said busy called station goes idle.

2. The telephone switching in accordance with claim 1 wherein the executive ringback circuitry further includes

means for alerting said busy called station for a predetermined time interval that executive ringback is to be effected, and

means for controlling the duration of said predetermined time interval.

3. The telephone switching system in accordance with claim 1 wherein the executive ringback circuitry further includes

means, activated by said enabling means, for providing an executive ringback acknowledgment signal for a predetermined time interval to said calling station in response to said switchhook flash, and

means for controlling the duration of said predetermined time interval.

4. The telephone switching system in accordance with claim 1 wherein the executive ringback circuitry furthher includes

means for automatically denying executive ringback to said calling station when said called station is busy as a result of a previous camp-on connection, and

means for notifying said calling station that executive ringback is denied.

5. The telephone switching system in accordance with claim 1 wherein the executive ringback circuitry further includes

means for detecting a return to an idle condition of said called station at the conclusion of said connection between said called station and said third party station,

means, responsive to said detection of a return to an idle condition of said called station, for supplying a predetermined number of ringing signals to said calling and called stations, and

means for establishing a talking path between said calling and called stations in the event both said calling and called stations go off-hook during said predetermined number of ringing signals.

6. The telephone switching system in accordance with claim 5 wherein the executive ringback circuitry further includes

means, activated by said calling station going off-hook in response to said ringing signals within said predetermined number of said signals, for disconnecting said ringing signal supply means from said calling station,

means for supplying an audible ringback signal to said calling station, and

means, activated by said called station going off-hook in response to said ringing signals within said predetermined number of said signals, for disconnecting said ringback signal supply means from said calling station.

7. The telephone switching in accordance with claim 5 wherein the executive ringback circuitry further includes

means, activated by said called station going off-hook in response to said ringing signals within said predetermined number of said signals, for disconnecting said ringing signal supply means from said called station,

means for supplying an audible ringback signal to said called station, and

means, activated by said calling station going off-hook in response to said ringing signals within said predetermined number of said signals, for disconnecting said ringback signal supply means from said called station.

8. The telephone switching system in accordance with claim 5 wherein the executive ringback circuitry further includes

means for detecting a failure of said calling station to respond to said ringing signals within said predetermined number of said signals, and

means, activated by said detecting means, for releasing said seized executive ringback circuitry and thereby releasing said crosspoint connections through said multistage switching network at the termination of said predetermined number of ringing signals.

9. The telephone switching system in accordance with claim 5 wherein the executive ringback circuitry further includes

means, activated by said calling station going off-hook and then on-hook, for releasing said seized executive ringback circuitry prior to said called station goind idle in the event a user of said calling station wants to abandon an executive ringback connection.

10. Circuitry for controlling the establishment of executive ringback connections between a calling station having a class of service which permits it to effect ringback call connections and a busy called station, said called station engaged in a connection with a third party station, said circuitry comprising

means, responsive to a call from said calling station to said called station, for detecting a busy condition of said called station, and

means, subsequently activated by said detecting means and responsive to a switchhook flash from said calling station, for effecting the establishment of call connections between said calling station and said busy called station at the conclusion of said connection between said third party station and said busy called station.

11. Executive ringback circuitry comprising

means for seizing said circuitry in response to a call from a calling station having a class of service which permits it to effect executive ringback call connections to a busy called station,

means, responsive to a receipt of a switchhook flash from said calling station, for establishing executive ringback connections between said calling station and said busy called station, and

means, activated by said establishing means, for supplying an executive ringback signal over said established connections to said calling and called stations for a predetermined time interval.

12. The executive ringback circuitry in accordance with claim 11 further comprising

means, activated upon termination of said executive ringback signal, for holding said seized executive ringback circuitry and said established connections between said calling and called stations until said called station goes idle,

means for detecting a return to an idle condition of said called station, and

means, responsive to said detection of a return to an idle condition of said called station, for supplying a predetermined number of ringing signals to said calling and called stations.

13. The executive ringback circuitry in accordance with claim 12 further comprising

means, activated by said calling station going off-hook in response to said ringing signals within said predetermined number of said signals, for disconnecting said ringing signal supply means from said calling station,

means for supplying an audible ringback signal to said calling station, and

means, activated by said called station going off-hook in response to said ringing signals within said predetermined number of said signals, for disconnecting said ringback signal supply means from said calling station.

14. The executive ringback circuitry in accordance with claim 12 further comprising

means, activated by said called station going off-hook inn response to said ringing signals within said predetermined number of said signals, for disconnecting said ringing signal means from said called station,

means for supplying an audible ringback signal to said called station, and

means, activated by said calling station going off-hook in response to said ringing signals within said predetermined number of said signals, for disconnecting said ringback signal supply means from said called station.

15. The executive ringback circuitry in accordance with claim 12 further comprising

means for detecting a failure of said calling station to respond to said ringing signals within said predetermined number of said signals, and

means, activated by said detecting means, for releasing said seized executive ringback circuitry at the termination of said predetermined number of ringing signals.

16. The executive ringback circuitry in accordance with claim 14 further comprising

means, activated by said calling station going off-hook and then on-hook, for releasing said seized executive ringback circuitry prior to said called station going idle in the event a user of said calling station wants to abandon an executive ringback connection.