Private branch exchange with resumption of interrupted communication

• US 5,410,591 A
• Filed: 07/07/1994
• Issued: 04/25/1995
• Est. Priority Date: 05/08/1991
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takahashi, Takumi
• Primary Examiner(s): Dwyer, James L.
• Assistant Examiner(s): Hunter, Daniel S.
• Application Number:
  US08/271,587
• Time in Patent Office: 292 Days
• Field of Search: 379/201, 379/210, 379/211, 379/212, 379/162, 379/163, 379/62, 379/393
• US Class Current: 379/215.01
• CPC Class Codes: H04M 3/42314 in private branch exchanges
• CPC Class Codes: H04M 3/4283 Call holding circuits
• CPC Class Codes: H04M 3/58 Arrangements for transferring received calls from one subscriber to another; Arrangements affording interim conversations between either the calling or the called party and a third party substation line holding circuits H04M1/80
• CPC Class Codes: H04Q 11/0428 Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
• CPC Class Codes: H04Q 3/627 Details

Abstract

If a communicating terminal connected to a communication line in a private branch exchange system is disconnected from the communication line, then, on the basis of call identifying information contained in an interruption message and in a resumption message, communication is put on hold and is subsequently resumed after the terminal is re-connected. This allows the terminal to be moved between the same or different communication lines while preventing loss of communication.

Claims

1. A private branch exchange system for interrupting and resuming communication of a terminal of the private branch exchange with another terminal over a transmission line, comprising:

means for interrupting a call of the private branch exchange terminal;

selection means for selecting and storing call identifying information associated with the private branch exchange terminal in such a manner that a plurality of interrupted calls will not receive identical call identifying information by said selection means;

means for informing the private branch exchange terminal of the call identifying information selected by said selection means;

means for retrieving call identifying information designated by the private branch exchange terminal; and

means for resuming one of the plurality of interrupted calls based on the call identifying information designated by the private branch exchange terminal.

2. The system according to claim 1, wherein when the private branch exchange terminal is informed of the call identifying information, said private branch exchange terminal is placed in an idle state and displays the contents of the call identifying information.

3. The system according to claim 1, further comprising means for comparing call identifying information in the selecting means with the call identifying information designated by the private branch exchange terminal and wherein if call identifying information having a value identical with the call identifying information designated by the private branch exchange terminal does not exist in the selection means, resumption of communication is refused.

4. A private branch exchange system, comprising:

reception means for receiving an interruption message and a resumption message transmitted from a terminal;

interruption means for interrupting a call in communication when said reception means receives the interruption message; and

storage means for storing a correspondence between call identifying information included in the interruption message and the call interrupted by said interruption means,

wherein if the interruption message received by said reception means does not include call identifying information, said storage means stores a correspondence between a terminal number included in the interruption message and the interrupted call, and

said interruption means resumes the interrupted call in accordance with either call identifying information included in the resumption message received by said reception means or a terminal number included in the resumption message and with the correspondence stored in said storage means.

5. The system according to claim 4, further comprising retrieval means for retrieving identifying information corresponding to the terminal number included in the interruption message received by said reception means,

wherein said storage means stores a correspondence between the identifying information retrieved by said retrieval means and the interrupted call, if the interruption message received by said reception means does not include call identifying information.

6. The system according to claim 5, wherein said retrieval means further comprises second storage means for storing a correspondence between the terminal number and the identifying information.

7. The system according to claim 4, wherein said interruption means releases the call from interruption based upon the call identifying information included in the resumption message if the resumption message received by said reception means includes the call identifying information, and if the resumption message does not include the call identifying information, said interruption means releases the call from interruption based upon the terminal number included in the resumption message.

8. A call control method of an exchange system comprising the steps of:

receiving an interruption message from a terminal of the exchange system in communication;

selecting and storing call identifying information associated with the exchange system terminal in such a manner that said call identifying information does not coincide with call identifying information associated with other terminals based on the interruption message received in said receiving step;

interrupting a call of the exchange system;

informing the exchange system terminal of the call identifying information selected in said selecting step;

retrieving call identifying information designated by the exchange system terminal; and

resuming one of the plurality of interrupted calls based on the call identifying information designated by the exchange system terminal.

9. The method according to claim 8, in which the terminal is informed of said call identifying information associated with the terminal so as to be displayed at the terminal.