Enhanced overflow call processing

Details Enhanced overflow call processing Enhanced overflow call processing

1996-01-11

2001-12-11

Tsang, Fan (Department: 2645)

Telephonic communications

Plural exchange network or interconnection

With interexchange network routing

C379S221030, C379S266040

Reexamination Certificate

active

06330323

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to routing a telephone call to an alternate termination when the call cannot be completed to an originally selected termination.
2. Background Information
Many businesses desire that calls which cannot be completed to their intended terminations be rerouted to a secondary or alternate termination. Calls may fail to complete for a variety of reasons. For example, the intended termination may refuse the call or may be unable to accept it. A customer dialing an 800 number might initially be routed to an understaffed call center. Rather than have the customer receive a poor grade of service, such as an unacceptably long wait, the call center manager may prefer to redirect the call to a secondary termination which may be able to provide a higher grade of service.
A typical prior art telephone network
100
, which provides call redirection, is shown in
FIG. 1
, as having three network switches
102
,
104
and
106
are connected by trunks
122
,
124
and
126
. Each switch
102
,
104
and
106
may also be connected to one or more local exchange networks (LEN) and/or one or more customer premise equipment (CPE), represented by blocks
110
,
112
and
114
, respectively. Each LEN/CPE is connected to one or more terminations, such as standard telephones or private branch exchanges (PBX), represented by blocks
111
,
113
and
115
, respectively. Each switch is also communicatively coupled to at least one network database
108
over signaling network
128
.
Network
100
is exemplified by U.S. Pat. No. 5,369,695 to Chakravarti et al. In Chakravarti et al., a telephone network switch
102
is arranged so that after forwarding an incoming call from LEN/CPE
110
to an intended terminating switch
104
, switch
102
responds to any one of a number of conditions requiring redirection of the call by redirecting the call to an alternate termination, switch
106
, identified as a function of a redirect code derived from associated calling information. Such conditions include the case of ring no answer and the case in which an answering party requests such redirection. The switch obtains the redirection code from a centralized network database
108
which derives the redirection code from calling information supplied by the switch.
Chakravarti et al. describes call redirection in response to three conditions: ring no answer, busy and post ringing redirection request. However, call redirection may be desired in response to any condition which prevents call completion. Examples of such conditions are: network congestion, transmission line outage, switch failure and LEN or CPE inability to complete the call. Chakravarti et al. does not deal with these conditions. In addition, Chakravarti et al. describes performing the same call redirection in response to all three conditions. It is desirable to vary the redirection performed depending upon the condition encountered.
Another typical prior art redirection scheme is described in U.S. Pat. No. 5,253,288 to Frey et al. In Frey et al., a call from originator
111
is initially extended through a toll network
100
toward the first destination
113
; if the toll network
100
is congested and cannot reach an egress switch
104
to access the first destination
113
or if a local exchange network
112
connecting the first destination
113
to the toll network
100
is congested, or if a first destination PBX
113
cannot be reached from the toll or local network because all access channels thereto are blocked, or if the first destination PBX
113
is congested or attendants are unavailable, an indication that the call cannot be completed to the first destination
113
is sent back to the ingress switch
102
of the toll network for that call. The call is then redirected from the ingress switch
102
of the toll network to an alternate destination
115
. If the first choice destination
113
is a PBX and the PBX rejects a call, the reason for the rejection can be used for altering the choice of an alternate destination or for canceling a potential redirection.
Frey et al., describes redirection of calls using tables organized around “non-existent” switch numbers. When a call having an indication that it is to be directed to a non-existent switch enters a switch, the non-existent switch number is translated within the switch to provide the real number of the destination switch. Frey et al., describes providing multiple alternative destinations by using tables to store a plurality of destination entries and incrementing from one table entry to the next. Frey et al. also describes altering the choice of an alternate destination based on the reason a call was rejected, but does not describe a mechanism for accomplishing this. The method described in Frey et al. provides limited flexibility for call redirection.
A need exists for improved control over multiple redirection of calls to upgrade the quality of service currently available to businesses and subscribers.
SUMMARY OF THE INVENTION
The system and method for enhanced call redirection provides call redirection of a call from one termination to at least one alternate termination in response to the failure of a call to be completed. In addition, it provides a hierarchical, user-configurable capability to redirect calls differently depending upon the reason the call was not completed.
In operation, a call enters a telephone network through an originating switch. The originating switch queries a network database to obtain routing information needed to route the call. Using this routing information, the originating switch routes the call to a terminating switch which attempts to complete the call to a currently selected termination. The originating switch then determines whether the call was completed to the currently selected termination. If the call was not completed, the originating switch releases the call from the terminating switch and queries the network database for a second termination for the call. The originating switch then routes the call to a terminating switch coupled to the second termination.
The originating switch queries a network database for an alternate termination for the call each time the originating switch detects that the call cannot be completed to the current termination. The network database determines the alternate termination for each query based on information regarding the reason the call was not completed. This information is supplied by the originating switch in the query message. The determination is controlled by a hierarchical set of multi-branch overflow statements which are configured by the user.
A set of overflow statements is selected by the network database based on the original termination of the call. The set of overflow statements is searched hierarchically until an active overflow statement is found. This overflow statement then controls all queries relating to that call. The reason the call was not completed is used to select either an alternate termination to which the call is to be routed or a particular treatment, such as a busy signal or network message, which is to be applied to the call. If an alternate termination is selected, the originating switch routes the call to the alternate termination. The process then repeats until either the call is completed, the overflow statement specifies a treatment is to be applied, or a predetermined number of completion attempts to alternate terminations have occurred.


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