Telephonic communications – Special services – Service trigger
Reexamination Certificate
1998-11-20
2001-06-26
Smith, Creighton (Department: 2742)
Telephonic communications
Special services
Service trigger
Reexamination Certificate
active
06252954
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to telecommunications systems, and more particularly, relates to a system and method for delaying the ringing of a line in a flexible call forwarding environment.
In the late 1970s and early 1980s, American Telephone & Telegraph Company (AT&T) developed an early species of common channel interoffice signaling (CCIS). CCIS is essentially a network architecture for a switched telephone network in which information about a telephone call is transmitted over high speed data links separate from the voice circuits used to transmit the signals of the call itself. Early in the development of CCIS, it was recognized that the interoffice data signaling links could be designed to provide high speed data regarding whether a call could be completed prior to assigning trunk capacity to set up the voice link, Thus, with CCIS the identity of the called number can be transmitted over the interoffice signaling data links from the originating central office to the terminating central office. The terminating central office is the central office that services the called number. If the called number is busy, then data providing this information is transmitted back over the interoffice signaling link to the originating central office that locally provides an audible busy signal to the caller. Therefore, no long distance trunk capacity is occupied during this process, and the voice circuits remain free for other uses. If the called number is not busy, various devices in the network respond to the information about this call to assign interoffice trunks to set up a connection for the call. While the call is being set up, the originating central office, based on a signal from the terminating central office, returns an audible ring back tone (RBT) to the caller. Once the called number is answered, an answer signal is passed from the terminating central office to the originating central office, the ring back tone is terminated, and the call is completed.
The public switched telephone network evolved in the 1980s to a complex and very versatile system, most of which supports and is controlled by a form of CCIS. The basics of this network were designed by AT&T. It is commonly referred to as the advanced intelligent network (AIN). Such an advanced intelligent network is shown in
FIG. 1
, and the AIN forms the environment of the present invention.
In the AIN, the same signaling path described above that is used for basic call set up, take down and routing, is also used to provide enhanced custom calling features and to control the operation of billing equipment and maintain billing records. One enhanced calling feature that may be delivered by the AIN is flexible call forwarding (FCF). When a subscriber/called party activates FCF, FCF automatically forwards an incoming call from a calling party to terminating equipment associated with a directory number that the called party has chosen. The called party may accept the call, reject the call, transfer the call, etc.
Any call directed to a subscriber's number is identified as a flexible call forwarded call by a query sent to the service control point of the AIN. Once the call is identified as a flexible call forwarded call, the service control point selects a service node (SN) to forward the call to in association with predefined destination terminating equipment to forward the call. The call is routed through a service switching point (SSP) (also referred o as an AIN central office) serving the service node, and then to the service node. The service node receives the call from its serving SSP (also referred to as hosting SSP) over an Integrated Service Digital Network (ISDN) interface. The service node may accept or reject the call from its serving SSP, and the service node provides an acceptance or rejection indication to its serving SSP. If the call is accepted by the service node, the public switched telephone network will seize a voice channel and provide RBT to the caller. The service node may choose to reject the call with a busy indication.
As described above, special handling of a call is necessary for an enhanced communication service, such as FCF. Special handling typically includes routing the call to a separate system or network element, such as a service node. The service node then handles the remainder of the call by interrupting the normal call flow from the calling party to the called party, implementing the subscriber's service, and reoriginating the call on the service node for completion of the call to the called party or other designated location.
One problem encountered with FCF is that the service node immediately accepts a call from a calling party before the call is connected to the called party. Thus, while the service node may be searching to locate the terminating equipment of the called party and receive an acceptance or rejection of the call from the called party, the calling party hears ringing and believes that the called party is not answering his or her telephone. Thus, the caller's perception of ringing begins the moment that the service node accepts the call although the called party's telephone has not begun to ring.
Another problem encountered with FCF is that the service node immediately accepts a call before the service node receives a busy or ringing tone from the called party's terminating equipment. As a result, the service node immediately plays ringing to the calling party regardless of whether the status of the called party's terminating equipment is busy. Thus, if the called party's telephone is busy, then the calling party may hear ringing and then hear a busy signal which can be annoying or confusing to the calling party.
Thus, in a flexible call forwarding environment, there is a need for a method and system that does not play ringing to the calling party until the call has been accepted or rejected by the far-end terminating equipment of the called party.
The present invention solves the above-described needs by providing a system and method for delaying the ringing to a calling party placing a call to a called party in a flexible call forwarding environment. The resolution to this issue is to use a settable timer to indicate when the service node should accept the flexible call-forwarded call. This timer, referred to as the service node acceptance timer, may allow the called party's acceptance or rejection of the flexible call-forwarded call to be detected by the service node before the service node's acceptance of the call. Instead of immediately causing ringing to be heard by the caller, the service node may detect the called party's terminating equipment as being busy and reject the call, resulting in a busy tone being played to the caller. Alternatively, the service node may detect the called party's acceptance of the call and start ringing to the calling party.
In one embodiment, the invention relates to a method or a system for delaying the ringing of a line until the status of the communication is determined when providing an advanced service. Upon transmitting the communication to a first network element, such as a service node, for forwarding to a forwarding number, a switch timer for a first predetermined time period is started. Upon receiving the communication at the first network element, an acceptance timer for a second predetermined time period is started. The second predetermined time period is less than the first predetermined time period and may be referred to as the service node acceptance timer. During the processing of the communication, a determination is made as to whether the acceptance timer has expired. If so, then the communication may be accepted at the first network element and a ring signal may be played to the calling party. If the acceptance timer has not expired, then a determination is made as to whether the first network element has received status information from the forwarding number. If the first network element has received status information, then the communic
BellSouth Intellectual Property Corporation
Ewing, IV Esq. James L.
Kilpatrick & Stockton
Smith Creighton
Tocups, Esq. Nora M.
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