Note: Descriptions are shown in the official language in which they were submitted.
. CA 0223S977 1998-04-27
SELECTIVE CALL WAITING DISABLE SERVICE FEATURE
FOR ANALOG TELEPHONE EQUIPMENT
Field of the Invention
s The invention relates to a method and apparatus for providing telephone
service features for analog telephones and more particularly to a method and appaldl~ls
for providing a selective call waiting service feature.
Background
Call waiting is a well know service feature that gives an analog telephone user
o th~e capability of being notified during a current telephone call if a further telephone
call is being attempted to the user's number. Referring to telecommunication
arrangement 100, as shown in Fig. 1, the calling station 101 attempts a call while the
called station 109 is presently in the midst of another call, for example with station
103 or 1 1 1. This call attempt from calling station 101 is transmitted through switch
104, network 106, such as the public switched telecommunications network, to switch
108. Switches 104 and 108 may be any telephone switches of the type that providecall features such as call waiting, such as a 5ESS-2000(~) by Lucent Technologies
Incorporated located in Murray Hill, New Jersey.
Connected to switch 108 on a shared analog line are station 109 and data
station 1 10. The switch 108 provides the standard call waiting feature for stations 109
and 110. In response to the call attempt from station 101, both the stations 109 and
110 are notified of the dllelllpl~d incoming call by means of a subtle tone that is
audible to a human using a handset of station 109, or a similar device. This tone is
inlçnt1s~1 to notify the party using station 109 of an incoming call without interrupting
the call-in-progress with another party using another station, e.g. 103 or 1 1 1. The
non-called party of the call-in-progress is not notified by the tone in the same way that
the party using station 109 or 1 10 is notified; however, the blocking by switch 108 of
the tone to the non-called party leaves a subtle, often noticeable signal drop out during
the conversation.
This standard call waiting service feature is popular because it provides a party
using analog telephone station 109 the equivalent of two line service with only one
analog line. The main problem to human users is that the notification tones or beeps,
which may or may not be distracting during on-going conversations. In some service
areas a tone sequence prefix code, for ex~mp!e *70, c,ln be entered by the user of
station 109 or 110 before an outgoing telephone call to disable the call waiting service
feature; however, there is no similar prefix code sequence to disable call waiting by an
incoming call. Additionally, in some areas, the call waiting service feature provider
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has not implemented a call waiting disable for the call waiting feature by the user.
Thus, for incoming calls and in some areas all calls cannot have the standard call
waiting service feature disabled wilhout completely dropping call waiting as a service
feature.
One known approach to disabling the call waiting is taken in U.S. Patent
Number 5,359,598 issued to Steagall et al. in a non-POTS setting in which a
conference call set-up packet disab]es call waiting at the voice processor of the called
party. The purpose of disabling the call waiting in Steagall et al. is the conclusion that
a conference call within the special system is a higher priority than any subsequent
0 call. When the conference call is over, the voice processor returns the call waiting
feature to its previous active status. This patent focuses on making digital signal
tr~n~mi~sion and digital voice processing transparent to the users, so its focus is
clearly limited to the disabling of call waiting for voice conference calls.
For incoming data tr~n~mi~sions on an analog line, where users either cannot
s disable call waiting or where the service provider does not allow any disabling of call
waiting, a tr~n~mi~ion, for example from data station 102 to data station 110, can be
cc~rrupted and/or interrupted by the standard call waiting feature. The standard 250
millisecond call waiting tones which are injected into the user's receiving circuit
corrupt the frequency shift keying and phase shift keying signals transmitted to the
user's data equipment, such as a modem or a facsimile m~hine. Similarly, the 250milli~econd blanking which is mearlt to prevent the other party or parties to a
conversation from hearing the call waiting tones corrupts any data from the user's data
equipment back to the remote data equipment. Such data corruption caused by the call
waiting tones leads to loss of data synchronization and file corruption. If the loss of
synchronization becomes so large that recovery is not possible, most modems and
facsimile machines will drop the connection completely leading to both a corruption
of' data and an interrupted and incornplete data transfer. Both results are veryundesirable.
Sllmmarg of the Invention
Briefly stated, in accordance with one aspect of the invention, the foregoing
problems are solved by providing a method which includes receiving at a call waiting
feature providing switch a call incoming to a subscriber, determining if the selective
ca.ll waiting disable feature is active for this subscriber and if it is not active
continuing with normal call processing and setting-up the incoming call, otherwise
3s determining if a directory number of this incoming call is on a list of selective call
waiting disable directory numbers. If the directory number of the incoming call is not
on the list of selective call waiting disable directory numbers the method continues
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with normal call processing and sets-up the incoming call, otherwise the method
disables call waiting and then continues with normal call processing and sets-up the
incoming call.
In accordance with another aspect of the invention, the foregoing problems are
s solved by providing a method which includes sending to a call waiting featureproviding switch a call incoming to a selective call waiting disable subscriber having a
selective call waiting disable prefix code and an identification code, determining if
selective call waiting disable is active and if it is not active continlling with normal
call processing and setting-up of the incoming call, otherwise determining if the call
o has a prefix code. If the call does not have a prefix code, the method continues with
normal call processing and sets-up the incoming call, and if it does have a prefix code,
the method determines if an identification number of the incoming call is on a list of
selective call waiting disable identification numbers. If the identification number is
not on this list of selective call waiting disable identification numbers the method
15 continues with normal call processing and sets-up the incoming call, otherwise the
method disables call waiting; and continues with normal call processing and sets-up
the incoming call.
Fig. 1 is a block diagram of a prior art telepl-~, ne arrangement for providing
standard call waiting features to its .~tt~çhP~l subscribers.
Fig. 2 is a block diagram of a telephone arrangement for providing selective
call waiting disable service features according to the present invention to its attached
subscribers.
Fig. 3 is a flow diagram of one embodiment of a selective call waiting disable
service feature.
Fig. 4 is a flow diagram of a second embodiment of a selective call waiting
disable service feature.
Fig. 5 is a flow diagram of a third embodiment of a selective call waiting
se-rvice feature.
DetailedD~s~ ;l.lion
Referring now to Fig. 2, an arrangement 100' is shown. The primary
difference between arrangement 100' and arrangement 100' shown in Fig. 1 are theprogr~mmin~ and hardware changes to telephone switch 108' in order to provide
pr,ocessing haldw~e and software to implement a method for providing a new call
waiting feature called Selective Cal] Waiting Disable (SCWD).
3s Referring now to Figs. 2 and. 3, a flow diagram of a method 300 according to
the present invention is explained. Method 300 starts with step 302 which is thereceipt of an incoming call to a directory number of a subscriber of switch 108'
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(shown in Fig. 2). From step 302, lhe incoming call progresses to step 304 where the
mLethod determines whether the Selective Call Waiting Disable feature is active, i.e.
the subscriber has chosen this feature for his or her service, for the subscriber
corresponding to this directory nurnber. If the subscriber to which the incoming call is
directed has the SCWD feature activated, method 300 progresses to step 306 and if the
subscriber does not have the SC~I) feature activated, method 300 progresses to
default step 310. At step 306 method 300 determines if the directory number ofthe
calling station from which the incoming call originated is on a list of directory
mlmbers authorized by the subscriber to disable call waiting for the subscriber as
0 pl epaLLdlion for an incoming call to the subscriber. If the directory number of the
calling station is on the list of directory numbers authorized to disable call waiting,
method 300 progresses to step 308, otherwise the method 300 progresses to default
step 310. The method 300 gets the directory number of the calling station from such
sources as ANI data field of the incoming call or the ICLID field of the incoming call.
Sl:ep 308 disables the call waiting feature for the subscriber for the duration of the call
which is from an authorized directory number and then progresses to default step 310.
Default step 310 is the beginning oi' normal POTS incoming call processing, which is
where the incoming call will eventually progress to, if the caller does not hang-up
prematurely. Beyond step 310, call processing is as it was previously implemented,
20 which includes resetting any call waLiting after being disabled upon termination of the
call. Thus, normal call processing at this point includes resetting from any prefix code
disabling or any SCWD disabling upon termination of the call.
Thus, method 300 allows calls from selected stations attached to selected lines
having selected directory numbers to a disable call waiting of the subscriber to the
2s feature. It is envisioned that, at least in part, callers authorized to disable call waiting
will be computers and f~imile machines attempting, and hopefully succee~ling, atuncorrupted data tr~n~mi.~ions. As mentioned previously, the call waiting 'beep' can
caLuse data errors and/or loss of synchronization and a related loss of connection. One
such situaLtion is when a call-back arrangement has been made between a user and a
30 dial-up server. When the server calls back, it would be very desirable that a call
waiting feature of the user be disabled and therefore non-disruptive of the datatraLnsferred during a call-back data tr~n.cmi~sion session. Similarly, for a non-callback
server which periodically dials up various user data stations to upgrade files or to
transfer files, it would be similarly desirable that a call waiting feature of the user be
35 disabled and non-disruptive of the data transmitted during a computer origin~te~ data
tr:ln~mi.~ion session.
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Referring now to Fig. 4, a method 400 for SCWD according to another aspect
oi-'the invention will be described. Method 400 starts with step 402 which is the
receipt of an incoming call to a directory number of a subscriber of switch 108'(shown in Fig. 2). From step 402, the incoming call progresses to step 404 where the
s method determines whether the Selective Call Waiting Disable feature is active, i.e.
whether the subscriber has chosen this feature for his or her service, for the subscriber
corresponding to this directory number. If the subscriber to which the incoming call is
directed has the SCWD feature activated, method 400 progresses to step 406 and if the
subscriber does not have the SCWD feature activated, method 400 progresses to
0 default step 412. At step 406 method 400 determines if the incoming call contains a
prefix code for disabling call waiting. If the incoming call does have such a prefix
code, method 400 progresses to step 408, and if the incoming call does not have such a
prefix code, method 400 progresses to default step 412. At step 408, method 400
determines if the incoming call contains an identification number which is on a list of
identification numbers authorized by the subscriber to disable call waiting for that
su.bscriber's stations 109,110 as ple~aldtion for the incoming call. If the identification
mlmber, which is provided by the calling station, such as station 102, is on the list of
identification numbers authorized to disable call waiting, method 400 progresses to
step 410, otherwise the method 400 progresses to default step 412. The identification
20 number, such as a 'personal identification number', is sent by the calling station either
as a separate field with the prefix code, or as an additional code. Further, thesubscriber pre-sets with switch 108' the list of identification numbers which he or she
au,thorizes to disable call waiting. Step 410 disables the call waiting feature for the
subscriber for the duration of the call and then progresses to default step 412. Default
2s step 412 is the beginning of normal POTS incoming call processing, which is where
thle incoming call will eventually progress to, if the caller does not hang-up
prematurely. Beyond step 412, call processing is as it was previously implemented,
which includes resetting any call waiting that had been disabled. Thus, normal call
proces~in~ at this point includes resetting from any prefix code disabling or any
30 SCWD disabling upon t~rmin~tion of the call.
Thus, method 400 allows calls from selected stations transmitting both SCWD
prefix codes and authorized identification numbers to a disable call waiting of the
subscribers to disable their respective SCWD features. It is envisioned that, at least in
part, calling stations, such as station 102, authorized to disable call waiting will be
35 computers attempting, and hopefully succee.ling, at data transmissions as mentioned
in regard to method 300. Method 400 is more flexible than method 300 in that thesubscriber is not required to know the directory number of the caller. Instead, the
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subscriber is only required to pre-set an identification number, thus allowing the caller
who knows an SCWD prefix code and identification number the flexibility to move
between directory numbers and hence locations.
For both methods 300 and 400 when call waiting has been disabled, a
s subsequent incoming call attempted during the time period that call waiting is disabled
will be routed to some type of 'busy' signal. Normally, this busy signal is the usual
slow beep - beep - beep with which users are f~mili~r. Users that subscribe to the
standard voice mail feature typically will be routed to an announcement that the line is
busy and an aural proln~ting to leave voice mail or try again later at an unspecified
o time. The try again later is a hit and miss operation since the caller can only guess
when the phone line will be available again.
In another aspect of the invention, method 500 shown in Fig. 5 takes the guess
work out of the when-to-try-again question of the caller receiving a busy signal.
Method 500 is especially useful since some data tr~n~mi~ions may be quite long, e.g.
for computer software updates or f~c~imi1e tr~n~miC;c;ions of 50 pages or more.
Method 500 has the capability to advise the subsequent caller, e.g., from station 111,
of an expected time when the data tr~ncmi~sion call will be over and the line likely to
be available. Method 500 does assume that time pal~llel~ such as start time,
estimated length of tr~n.smi.csion and/or estim~ted end of tr~n~mi~ion time are sent to
20 the switch 108' (shown in Fig. 2) by the calling station 102. Such information may be
tr;ansmitted in various ways. for example as a field of the prefix code that disables call
waiting or as an additional prefix code. This time data can be estim~ted by the
tr,~nsmitting station 102 by file size information and historical data transfer rates, and
projected time-of-day start of data tr~n~mi.~sion to the station 110. From this time data
25 an estim~ted end of ll~1s~l time is computed and announced to a subsequent caller as
part of the method 500. If the calling station sends the start time, data rate and file
size data for computer tr~n~mi~.C ions or page data for fAccimile tr~nC;mic;.~ions~ then
switch 108' can calculate an estimal:ed end of data tr~n.~mi~C;ion and availability of the
line for subsequent incoming calls. Similarly, the calling station that disables call
30 waiting, e.g. station 102, can calculate an estim~tecl end of data tr~n~mi.csion and
availability of the line for subsequent incoming calls and transmit that end time to
s~;vitch 108', such that switch 108' can announce, i.e. advise, anyone who makes a call
attempt during the data tr~n.cmi~sion of a good time to call back.
Specifically, method 500 st~rts with step 502 which is the receipt of an
35 incoming call to a directory number of a subscriber of switch 108' (shown in Fig. 2).
From step 502, the incoming call progresses to step 504 where the method determine
whether the SCWD feature is active, i.e. the subscriber has chosen this feature for his
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or her service, for the subscriber colTesponding to this directory number. If the
subscriber to which the incoming call is directed has the SCWD feature activated,
method 500 progresses to step 506 ~md if the subscriber does not have the SCWD
feature activated, method 500 progresses to default step 516. At step 506 method 500
determines if the incoming call contains a prefix code for disabling call waiting. If the
incoming call does have such a prefix code, method 500 progresses to step 508, and if
thle incoming call does not have such a prefix code, method 500 progresses to default
step 516. At step 508, method 500 determines if the incoming call contains an
id,entification number which is on a list of identification numbers authorized by the
o subscriber to disable call waiting for the subscriber as preparation for the incoming
call. If the identification number, which is provided by the calling station, is on the
list of identification numbers authorized to disable call waiting, method 500
progresses to step 510, otherwise the method 500 progresses to default step 516. The
identification number, such as a 'personal identification number', is sent by the calling
station either with the prefix code Ol as a separate field in addition to the prefix code.
Further, the subscriber pre-sets the list of identification numbers which he or she
authorizes to disable call waiting. Step 510 disables the call waiting feature for the
subscriber for the duration of the ca]l and then progresses to step 512. Step 512
determines if a time field that is either part of the prefix code or is a second prefix
20 code is greater than zero (which me~ms 00:00:00 as a midnight end point would have
to be avoided by at least one second more or one second less). If the answer is yes,
that means that end of tr~n~mi.c~ion data has been sent by the calling station, and the
method 500 progresses to step 514, otherwise method 500 progresses to default step
516. Step 514 processes the end of tr~n.emi~ion data and plepal._s a 'busy'
25 announcement, and then the method 500 progresses to step 516. Step 516 continues
with typical call processing except that any announcement made to a subsequent caller
while call waiting is disabled by a data transmission providing end of tr~n~mi~sion
data will include advice as to when lhe data tr~n.~mis.cion is likely to be over and when
the line is likely to be available for incoming calls. Like methods 300 and 400, this
30 call processing by switch 108' includes resetting call waiting, any prefix fields stored
in switch 108 ', and clearing any 'busy' signals or messages at the end of the data the
incoming call.
Thus, it will now be understood that there has been disclosed a method and
apparatus for a selective call waiting disable feature. While the invention has been
35 particularly illustrated and described with reference to preferred embodiments thereof,
it ~,vill be understood by those skilled in the art that various changes in forrn, details,
and applications. For example, the telephone switch may be sent file transfer duration
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data instead of time-of-day data in order to prepare the callback later advice. Further,
the local telephone switch could update the end of tr:ln.cmi.~sion time as it isrliimini~h~l It is accordingly intended that the appended claims shall cover all such
changes in form, details and applications.
