Note: Descriptions are shown in the official language in which they were submitted.
CA 02232168 1998-03-16 llP250CA
FIELD OF THE INVENTION
This invention relates to the field of
telephony, and in particular to a method of call
screening
BACKGROUND TO THE INVENTION
Telephone subscribers are often inconvenienced
by commercial or business calls at inappropriate times,
or by prank callers which call during nighttime hours.
Some central offices have a feature which attempts to
avoid the inconvenience, which allows a telephone
subscriber to receive calls only from a predefined list
of telephone directory numbers, and to block all others.
However it has been found that this feature is seldom
used due its inflexibility. For example, calls can be
received from all of the directory numbers on the list,
and all others are blocked, 24 hours per day, or until
disabled. If call blocking is to be done each evening
and disabled each morning, this must be done each day by
the subscriber, i.e. attendance must be made to the
feature twice per day. This is very inconvenient for
busy subscribers.
SUMMARY OF THE INVENTION
In accordance with the present invention,
subscribers can establish a screen of calling directory
numbers, and link the directory numbers which are on the
list to time intervals. Thus, for example, in one
embodiment, calls from different numbers on the list can
be allowed to be completed during time intervals linked
to specific time intervals, and all others blocked. In
another embodiment, incoming calls from all directory
numbers not on the list can be blocked during one or
plural time intervals, and calls from directory numbers
on the list can be allowed to be completed. In
accordance with another embodiment, separately or in
conjunction with the above embodiments, all calls can be
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allowed to be completed except for certain listed
directory numbers during intervals linked to the listed
directory numbers.
In accordance with an embodiment of the
invention, a method of call screening comprises
receiving a call to a subscriber directory number,
determining a calling directory number of the call,
checking a first list of calling directory numbers to be
affected by a screen and a second list of times during
which the directory numbers are to be blocked or
permitted through the screen to determine whether a call
incoming from the calling directory number should be
blocked at a real time contained within the times, and
completing the call to a line associated with the
subscriber directory number in the event the call is not
to be blocked at the real time of the call.
BRIEF INTRODUCTION TO THE DRAWINGS
A better understanding of the invention will be
obtained by considering the detailed description below,
with reference to the following drawings, in which:
Figure 1 is a block diagram of a system on which
the present invention can be carried out,
Figure 2 is a flow chart of steps of the present
invention,
Figure 3 is a diagram of contents of a memory in
accordance with an embodiment of the invention,
Figure 4 is a flow chart of steps of the present
invention,
Figure 5A is a diagram illustrating a time line
of blocked and unblocked periods, to aid understanding
another embodiment of the invention, and
Figure 5B is a diagram of contents of a memory
in accordance with an embodiment of the invention
relating to the timeline of Figure 5A.
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DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Figure 1 illustrates a block diagram of a
telephone switching system which can carry out the
invention, which is based on a telephone system
described in U.S. patent 4,615,028 issued September 30,
1986, invented by Conrad Lewis and Gino Totti, and in
U.S. patent 4,616,360 issued October 7, 1986, invented
by Conrad Lewis. In that system, a central control 1,
operating under control of programs stored in memory 3,
communicates with memory 3 and with at least one circuit
switch 5 and with at least one message switch 7 via bus
9. The control 1 controls circuit switch 5 to connect
calls between peripherals such as telephone sets 11 and
trunk circuits 13, and extends the peripherals' lines
connected to the peripheral switch 15 to circuit switch
5 for interconnection by sending control messages to the
peripheral switches via the message switch 7. A
processor 17 controls peripheral switch 15, and is
controlled by messages received via peripheral switch 15
from processor 1.
To implement the present invention, an auxiliary
memory or portion of an existing memory such as memory 3
stores a database such as will be described below. The
database 19 can be connected to bus 9 for access by the
processor 1, or can be connected for access by processor
17. The embodiment below will be described with
database 19 connected to bus 9, but a person skilled in
the art having read the aforenoted patents will
recognize how the database can be accessed and used in
conjunction with processor 17 instead.
With reference to Figure 2, in accordance with
an aspect of the invention, a subscriber lifts the
handset of a telephone ll (or does the equivalent by
pushing a button on a feature phone or virtual button
displayed on a computer associated with a telephone in a
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computer-telephone integration system (CTI), i.e. goes
offhook. Under control of processor 17, the peripheral
system connects a dual tone multifrequency (dtmf)
receiver to the offhook subscriber line via the
peripheral switch 15.
The subscriber dials a feature access code,
which is translated to a message by dtmf receiver 19 and
processor 17, and is sent via the message system to
processor 1. Under control of programs stored in memory
3, processor 1 then causes an automatic dialog to ensue
with the subscriber, by sending messages to processor 17
to cause a digital signal processor (dsp) 21 to be
connected to the offhook subscriber line and voice
synthesize prompt questions which are responded to by
the user keying dtmf digits. Alternatively, a voice
response unit is connected to the offhook subscriber
line to prompt questions and recognize the meaning of
spoken responses.
The prompt questions request the subscriber to
key in the directory number of a prospective caller
which is to be screened, and then to key numbers
corresponding to times which the calling directory
number is to be allowed to complete calls to the offhook
line. By keying e.g a # sign, the completion of a
sequence can be indicated.
Alternatively, instead of voiced prompts and
responses, if a CTI computer or other display is used in
conjunction with the offhook telephone, the prompts and
responses can be made by dialog box and keyboard.
In an embodiment of the invention, the directory
numbers are stored in a permissions list in database 19,
in a form such as is shown in Figure 3. This list is
comprised of an identity of the subscriber which has
invoked the feature, e.g. such as the subscriber
directory number, a list of prospective calling
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subscriber directory numbers which are to be allowed to
complete calls to the subscriber with the exclusion of
all other calls from directory numbers which are not on
the permission list during "blocked intervals", and a
S list of blocked time intervals during which all calls
other than those from directory numbers on the
permission list are to be excluded.
Following entry of the permissions list and
block times, the subscriber hangs up (goes on hook).
With reference to Figure 4, when a call is
received to be completed to the subscriber line, the
calling party's directory number is identified by the
system using automatic number identification (ANI), and
the identified directory number is checked against the
permissions list in the called party's database record,
e.g. as shown in Figure 3, by the processor l accessing
database l9. If the identified directory number is on
the permissions list, the call processor l controls
completion of the call to the subscriber line, e.g. by
ringing that line.
If the identified directory number is not on the
permissions list, the blocked intervals portion of the
database record is read under control of processor l,
and the blockout times are checked against a real time
clock contained in the switching system. If the real
time is outside the blocked intervals, the processor
controls completion of the call.
If the real time is inside one of the blocked
intervals, the call is not completed. It is preferred
that instead of merely returning continuous ringing tone
to the calling party to indicate non-completion of the
call, a voice unit should be connected to the line or
trunk on which the incoming call is carried, e.g. under
control of processor 17 via peripheral switch 15. The
voice unit can announce that incoming calls to the
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called subscriber are currently blocked. The voice unit
can also announce, if desired in implementation of the
service, the time periods in which the called lines
would be unblocked.
It should be noted that in this and other
embodiments, the directory numbers identify the
subscribers, and may be distinguished from
identification of the subscriber lines, since different
subscribers can have different directory numbers
associated with a single subscriber line. In the latter
case, for example, a subscriber having an identity of
one directory number can have a permission list relating
to the line, and another subscriber having an identity
of another directory number can have a permission list
relating to the same line. The two permission lists
need not correspond as to time, and can operate
independently of each other. Thus for example a
permitted incoming call for a first subscriber which is
not on the list of the other subscriber can ring the
line to reach the first subscriber even though it would
be otherwise blocked for the reason of not being
included on the permissions list of the other
subscriber.
Figure 5A is a timeline of a day, illustrating
another embodiment of the invention. As the example
shown, it is desired to block all calls except directory
numbers A, B and C during an interval 6:00 AM to 9:00
AM, and to further unblock calls in addition from
directory number D during the interval 8:00 AM to 9:00
AM.
In addition, it is desired to block only calls
from directory number D during the interval form 6:00 PM
to 7:00 PM.
During other periods, no calls are blocked.
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Reference is now made to Figure 5B which
illustrates contents of the database for the subscriber.
A first sublist 30 is a permissions list which contains
the directory numbers of calls which are to be blocked
during particular time intervals. In other words,
sublist 30 can be characterized as meaning "block all
calls except those incoming from the directory numbers
listed in the sublist, during linked time intervals".
A second sublist 31 contains directory numbers
of incoming calls which are to be blocked during
particular time intervals. In other words, sublist 31
can be characterized as meaning "block no calls except
those incoming from directory numbers listed in sublist
31, during linked time intervals".
Sublist 32 contains linked time intervals for
sublist 30, and sublist 33 contains linked time
intervals for sublist 31.
Each directory number in sublists 30 and 31
contain a pointer which links it to a respective sublist
32 or 33. Thus for example, the record of directory
number A has a pointer to a sublist 32 which contains
the time interval 6:00 AM - 9:00 AM (and can contain
other additional time intervals), the record of
directory number B has a pointer to a sublist 32 which
contains the time interval 6:00 AM - 9:00 AM, and the
record of directory number C has a pointer to a sublist
32 which contains the time interval 6:00 AM - 9:00 AM.
The record of directory number D in sublist 30 has a
pointer to a sublist 32 which contains the time interval
8:00 AM - 9:00 AM.
The sublist 31 contains a record of directory
number D and a pointer to a sublist 33, which contains
the time interval 6:00 PM - 7:30 PM.
The processor 1, in processing the data carried
in the sublists should ignore exclusions that result
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from time overlaps. Thus, in considering sublists 30 -
33, if a call to the subscriber from any directory
number arrives prior to 6:00 AM, it is completed. From
6:00 AM to 8:00 AM, all incoming calls from directory
numbers other than A, B and C are blocked, and from 8:00
AM to 9:0O all incoming calls from directory numbers
other than A, B, C and D are blocked.
From 9:00 AM to 6:00 AM the next day, no calls
are blocked, except for calls from directory number D,
which is blocked between 6:00 PM and 7:30 PM, since that
directory number is contained in sublist 31 (meaning,
"block no calls except block calls from directory number
D between 6:00 PM and 7:30 PM).
Once the screening schedule is setup, it is
repeated daily, which results in the subscriber not
having to enable and disable screening on an as needed
or on an as not desired basis, substantially reducing
attention and inconvenience to the user.
Further, the system can include different lists
and/or sublists for designated days, such as weekends
and holidays. Particularly if the content of the lists
and sublists are established on a display, e.g. by
displaying a time and date diary, the lists, sublists
and their content can be established to control the
screening far into the future, to include holidays which
do not conform to weekends, to conform to needs of
temporary expected visitors, etc.
The content of the sublists can be entered by
voiced or displayed prompts, as described earlier.
A person understanding this invention may now
conceive of alternative structures and embodiments or
variations of the above. All those which fall within
the scope of the claims appended hereto are considered
to be part of the present invention.
