Note: Descriptions are shown in the official language in which they were submitted.
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PROGRAMMABLE AUTOMATIC PREFIX DIALER FOR WIRELESS
TELEPHONE
Inventors: Howard B. Rosen, Robert M. Nelson
Field of the Invention
The invention relates to a method for automatically dialing a
predetermined telephone number prefix, such as an area code, when using a
wireless telephone, such as a cellular telephone, which method includes steps
for selectively changing the predetermined telephone number prefix and for
selectively overriding the automatic dialer. The invention also relates to an
apparatus for carrying out the method.
Background of the Invention
Local telephone calls have, for many years, been effected by dialing a
seven digit code. At one time, all long distance calls were handled by "long
lines"
operators who more or less manually established a routing for a given call.
However, since the late 1950's, direct dial long distance calling has been
widely
used. Directly dialed long distance calls involve the dialing of a first
prefix,
typically "1 ", to indicate to the telephone company apparatus that a long
distance
call is contemplated, then dialing a second prefix, the three digit area code,
before the local seven digit number of the called party is dialed. In this
manner,
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a long distance call can be carried out without the intervention of an
operator.
Variations of this process, typically dialing longer strings of numbers,
permits
international long distance direct dialing.
When this system was established, largely under the auspices of
American Telephone and Telegraph Company, it was believed that the allocation
of possible telephone numbers (including area codes) was adequate to handle
all demand for many years. However, it is becoming evident that such is no
longer the case. In particular, the remarkable proliferation in dedicated line
demand for fax machines and the like, and, especially, for modems which may
be used, inter alia, for connecting a computer to the Internet and other
networks,
has pushed the allocation of available lines, notwithstanding the application
of
various technological advances, to near the limit possible with the current
system.
One technological advance which promises to alleviate this problem for
a number of years is to require a calling party to dial the area code of a
called
party even when the two parties are within a common area code. Thus, one
would be required to dial a ten digit code even if the called party is next
door. It
will be readily apparent that this change will be highly inconvenient to many
persons who wish to continue the use of the traditional seven digit dialing
for
local calls. Accordingly it will be understood that a method and apparatus
which,
in such a contemplated modified telephone dialing system, permits the ongoing
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use of standard seven digit dialing for routine local calls from a telephone
wired
to a central facility would be highly desirable.
A similar problem which arises in a technically substantially different
communications device pertains to the use of wireless (e.g., cellular)
telephones
in an environment in which a caller will be required to enter the local area
code
prior to a entering a called party's seven digit number. Further, there is an
additional distinction because a cellular telephone, by nature, is highly
portable.
Thus, the "local" area code is a variable as a cellular telephone is moved
from
one area code to another. Therefore, the present invention is directed to
eliminating the need to manually enter an area code before instituting a local
call
from a cellular telephone and further provides for readily changing the local
area
code to be automatically entered ahead of the manually entered seven-digit
number and also for permitting conventional use of a cellular telephone to
make
long distance calls.
Objects of the Invention
It is therefore an object of the invention to provide an automatic prefix
dialer which eliminates the necessity for a calling party to manually dial any
predetermined code, such as an area code, prior to entering a called party's
local telephone number from a wireless telephone.
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It is also an object of the invention to provide a method which eliminates
the necessity for the calling party to dial the predetermined code from a
wireless
telephone.
It is a more specific object of the invention to provide wireless telephone
apparatus which effectively automatically transmits the predetermined code
before a manually-entered local telephone number of the receiving party is
transmitted.
It is a further object of the invention to provide a method wherein the
predetermined code is automatically transmitted before the telephone number
of the receiving party is transmitted.
In another aspect, it is an object of the invention to provide such method
and apparatus which includes a feature which permits the dialing of the
predetermined code to be selectively overridden when appropriate such as when
a long distance call is contemplated.
In yet another aspect, it is an object of the invention to provide a
method and apparatus by which the predetermined code may be easily changed
as the wireless telephone is moved from area code to area code.
Summary of the Invention
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Briefly, these and other objects of the invention are achieved by a
method, and apparatus for practicing the method, in which, before a calling
party
institutes a call on a cellular telephone, the area code is semi-permanently
stored in the cellular telephone. During the dialing process, after the
seventh
digit has been dialed and before an eighth digit has been dialed, a
determination
is made as to whether the "send" button has been actuated. If so, then the
stored area code is prefixed to the seven dialed digits, and the resulting ten
digit
number is transmitted. If not, then the dialing continues until the "send"
button
is actuated at which time the fully dialed number is transmitted. Typically,
the
latter condition indicates that a long distance call is in process. Thus, in a
preferred embodiment, a determination is made that eleven digits have been
dialed, and those eleven digits are transmitted. Because a cellular telephone
is
portable by nature, provision is made to update the automatically-prefixed
area
code when the cellular telephone is moved to a different area code.
Description of the Drawing
The subject matter of the invention is particularly pointed out and
distinctly claimed in the concluding portion of the specification. The
invention,
however, both as to organization and method of operation, may best be
understood by reference to the following description taken in conjunction with
the
subjoined claims and the accompanying drawing of which:
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FIG. I illustrates a telephone arrangement in which wired telephone
apparatus may be connected;
FIG. 2 is a schematic block diagram of an exemplary embodiment of the
apparatus;
FIG. 3 is a partially block, partially schematic diagram of apparatus for
practicing the present invention;
FIG. 4 is a block diagram of a more practical implementation of the
present invention; and
FIG. 5 is a detailed flow chart of the process of the present invention as
practiced in the variant apparatus shown in FIGs. 3 and 4.
Description of the Preferred Embodiment(s)
A telephone line 1, consisting of wires 1 A and 1 B, is connected to a
plurality of sockets 3, 5 and 7, mounted on walls 9, 11 and 13, respectively,
in
a household. Telephones 15 and 17 are connected, via lines 19 and 21,
respectively, to plugs 23 and 25 which are plugged into sockets 5 and 7,
whereby the telephones 15 and 17 are conventionally connected to the
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telephone line 1. Although FIG. 1 illustrates a situation in which a single
line
services a plurality of telephones, the invention is equally applicable when
the
telephone line services only a single telephone as will be discussed below.
The automatic prefix dialer unit apparatus is illustrated generally at 27 in
FIG. 1 and includes a plug 29, which mates with the socket 3, and a socket 31
which is similar to the socket 3. If the apparatus is remotely located from
the
socket 3, line pair 28 couples the prefix dialer unit 27 to the plug 29 as
will be
evident from FIG. 1. In addition, if the telephone line is servicing only a
single
telephone, then that telephone can be plugged into socket 31 of the prefix
dialer
unit 27. In fact, this would be possible even when the line 1 is servicing a
plurality of telephone lines. This feature eliminates the possibility that a
socket
will have to be used solely for the prefix dialer unit 27. That is, both the
apparatus 27 and a telephone can be plugged into the same socket 3.
Attention is now directed to FIG. 2 which is a block diagram of an
exemplary embodiment of the prefix dialer unit 27. (It will be understood by
those skilled in he art that a physical implementation may take diverse
forms.)
For clarity, the circuitry illustrated in FIG. 2 is shown single ended, it
being
understood that a voltage reference, e.g., ground potential, is conventionally
maintained throughout the circuitry.
Thus, in FIG. 2, the automatic prefix dialer unit 27 includes an off-hook
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detector 40 which, for example, employs a d-c voltage comparator 30 having a
signal input connected to the telephone line 1 and a reference input which is
fed
with a reference voltage from a suitable source 31. As is well known in the
art,
when the line changes from an on-hook to an off-hook condition, as when one
of the telephones 15, 17 (FIG. 1) is picked up, there is a consequent change
in
voltage -- usually a decrease in voltage -- across the line. This change is
detected by comparator 33 which compares the voltage on the line with the
reference voltage. Other arrangements could be used to detect the off-hook
condition as well known in the art.
The output of the off-hook detector 30 is fed to the input of a first one-
shot 32. When an off-hook condition is detected by the off-hook detector 40, a
triggering signal is sent to the one-shot 32 which responds by issuing an
output
pulse of predetermined (by the selection of timing components as well known in
the art) time length to a prefix dialer 33. A predetermined code, which, in
the
example, is the local three digit area code, is stored in a memory 34 in the
prefix
dialer 33.
The prefix dialer 33 responds to the leading edge of the output pulse from
the one-shot 32 by dialing the predetermined code stored in memory 34, e.g.,
the local area code, to relieve the calling party from the necessity of taking
this
step while placing a local call. This is achieved by using the predetermined
code
to activate a conventional tone sequencer 42 which sends, via line 35, the
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appropriate tone sequence to the telephone line 1. (While a conventional pulse
dialer can be used in place of the tone sequencer 42, the latter is preferred
because it operates much more quickly.)
The automatic prefix dialer unit 27 responds sufficiently quickly to the
sensed off-hook condition that the prefix dialing action of the dialer 33 is
essentially transparent to the calling party. Accordingly, the predetermined
code
is automatically dialed each time the receiver of the telephone is lifted (or
other
appropriate action taken) to place the telephone line in an off-hook
condition.
Thus, the calling party does not have to go through the inconvenience of
dialing
the predetermined code each time a local call is made, nor is it possible for
the
calling party to inadvertently dial a local number without the predetermined
code
first having been dialed.
However, provision must be made for direct dialing a long distance
number when desired, and the apparatus as described so far renders this
operation impossible if it is the local area code which is stored in memory 34
as
has been described. Still referring to FIG. 2, and, for convenience, assuming
positive logic throughout, a positive signal (logic "l") from the off-hook
detector
40, indicating that a telephone on the line has been picked up, triggers the
one-
shot 32 which issues a positive pulse (logic "1 ") to the prefix dialer 33 to
initiate
the dialing of the predetermined code stored in memory 34 as previously
described. In addition, the output of the one-shot 32 is also connected to a
first
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input of an AND-gate 41 and thus, at this time, delivers a logic "1" signal
thereto
until the one-shot 32 times out. Further, the output from the off-hook
detector 40
is also connected to the input of an inverter 36. Thus, when the off-hook
action
is taken, a logic "1,' signal is applied to the input of the inverter 36 such
that its
output is logic "0". The output of inverter 36 is connected to a second input
to
AND-gate 41 which is therefore not enabled under the conditions just
described.
The output of AND-gate 41 is connected to the trigger input of a second one-
shot 37 which will therefore
only be triggered when the AND-gate 41 is fully enabled.
The first one-shot 32 is configured to be non-retriggerable (i.e.,
application of a second trigger pulse while its output pulse is still logic
"1" has no
effect on the time length of the output pulse) and to have a time out which
may
be on the order of five to ten seconds, even though the prefix dialing
operation
rapidly takes place early in this time period. The second one-shot 37,
however,
has a substantially shorter time out which is greater than about 0.8 second,
and
is preferably about one to two seconds.
Consider now the operation of the apparatus when a user "flashes" the
telephone handset shortly after picking it up; i.e., when the user quickly
depresses and releases the flash hook plunger (or accordingly activates the
corresponding device on a telephone which does not have a plunger) for less
than about 0.8 second. If this step is taken before the first one-shot 32 has
timed
CA 02381119 2002-04-09
out, the prefix stored in memory 34 will already have been dialed by the
prefix
dialer 33, but the first input to the AND-gate 41 remains at logic "1".
When the user "flashes" the telephone, the output of the off-hook detector
40 briefly transitions to logic "0" and then back to logic "1 ". This second
transition
has no effect on the time out of the first one-shot 32 because it is
configured as
non-retriggerable. However, the first transition causes the output of the
inverter,
and hence, the second input to AND-gate 41 to briefly change to logic "1"
which
fully enables the AND-gate 41 to trigger the second one-shot 37. The output
pulse from the second one-shot 37 is applied to the input of an inverting
amplifier 38 which serves, during the time out period of the second one-shot
37,
to place, via line 39, a suitable voltage on the line 1 to emulate a manual
hang-
up; i.e., to emulate an off-hook to on-hook transition. When the second one-
shot
37 times out, the emulated hangup condition is removed, and a dial tone is
heard in the telephone handset. However, there is no action taken by the
prefix
dialer 33 as the one-shot 32 did not time out before the emulated hang-up
operation was completed (which causes another trigger pulse to be applied,
without effect, to the input of one-shot 32). The user is then free to dial
the full
long distance code desired from the telephone hand set, a result obtained by
merely "flashing" the telephone shortly after picking up the handset or taking
equivalent action with other types of telephones.
In the illustrated embodiment, the automatic prefix dialer unit 27 has been
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described as a separate unit. It will be apparent that the elements of device
27
can be integrated into the telephone instrument (15 or 17) so that it forms a
part
of the instrument.
A feature in a wireless telephone (e.g., a cellular telephone) requires a
different solution than in a fixed device, which must also take into account
the
inherent portability of such a wireless communications device.
Thus, attention is now directed to FIG. 3 which is a high level functional
block diagram of a cellular telephone 50 incorporating the present invention.
As
is conventional in the art, assuming that wireless communication has already
been established between a party using the cellular telephone 50 and another
party, conversation by the person using the cellular telephone is carried out
by
speaking into a microphone 51 and listening from a speaker 52. The microphone
51 conventionally transforms the sound pattern into an electrical signal which
is
amplified by audio amplifier 52 and then applied to modulation/demodulation
circuit block 55. Modulation/demodulation circuit block 55 drives duplex RF
circuitry block 56 which wirelessly transmits the signal from antenna 57. For
incoming signals representing the voice of the other party, the antenna 57
intercepts the wireless signals and sends them to the modulation/demodulation
circuit block 55 (via duplex RF circuitry block 56) where the demodulated
audio
signal is extracted, amplified by audio amplifier 54 and may be heard in
speaker
52. This explanation and the circuitry presented is, of course, somewhat
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simplified, but is sufficient to provide a background for explaining the
invention
which is in the dialing apparatus 60 (and corresponding method) of the
exemplary cellular telephone 50.
The dialing apparatus 60 includes a keypad 61 for entering digits during
the dialing process. As the first seven digits are entered, they are serially
transferred to a seven-character register (or the equivalent) 64. In addition,
as
each digit is entered via the keypad 61, a previously reset four-binary-digit
counter 63 is incremented. An area code is semi-permanently stored in a three-
character register (or the equivalent) 65, and the outputs from the register
65 are
applied as parallel inputs to an AND-gate array 66. The outputs from the AND-
gate array 66 are transferable in parallel to another three-character register
(or
the equivalent) 67. Thus, it will be understood that the area code semi-
permanently stored in the three-character register 65 may be controllably
transferred to the three-character register 67.
The seven-character register 64 and the three-character register 67 are
serially concatenated such that a full ten-character number can be stored
therein. The serial output from the three-character register 67 is applied as
one
input to an AND-gate 68 which drives one input to an OR-gate 69 which, in
turn,
controllably applies dialing digits to modulation/demodulation circuitry block
55.
The state (logic "1" or logic "0") of each of the four stages in the counter
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63 is applied as one input to either or both of AND-gates 70, 71. More
particularly, the positive logic outputs of the three lowest order stages of
the
counter 63 are applied as three of the four inputs to the AND-gate 70 whose
fourth input is coupled to a send button 62 such that depressing the send
button
applies a logic "1" to the fourth input of the AND-gate 70. Thus, it will be
seen
that, only if the counter 63 has an immediate value of "0111" and the send
button 62 has been depressed, will the AND-gate 70 be fully enabled.
The output from the AND-gate 70 is applied as a control input to the AND-
gate array 66 such that, under this condition, the area code semipermanently
stored in the register 65 will be copied into the three-character register 67.
In
addition, the output from the AND-gate 70, under this condition, will also
enable
one input to another AND-gate 74 which has its other input driven by a dial
clock
signal DCLK. The output from the ANDgate 74, under this condition, will
therefore be the dial clock which is applied as another input to the AND-gate
68.
Accordingly, the ten digits serially stored in the seven-character register 64
and
the three-character register 67 are clocked through the AND-gate 68, the OR-
gate 69, and to the modulation/demodulation circuitry block 55 for
transmission
to the commercial facility to which the cellular telephone is subscribed to.
Thus,
it will be seen that a local call has been made by dialing a seven-digit
number
and depressing the send button 62, notwithstanding a system requirement to
transmit ten digits including the local area code.
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When a telephone conversation has been concluded, an end button 75
may be depressed to carry out the usual functions in the cellular telephone
associated with that operation and also to apply a reset signal to the counter
63,
thereby resetting its contents to "0000" in anticipation of the next telephone
call
to be originated at the cellular phone.
Consider now the operation of the dialing apparatus 60 when a
conventional long distance call is to be dialed. In accordance with normal
practice, a "1" is first dialed followed by the area code of the target
telephone
and then by the seven-digit number within the area code of the target
telephone.
It will be noted that not only is the three-character register 67 concatenated
serially with the seven-character register 64, but also a single character
register
76 is concatenated with the three-character register 67, thus providing for
the
serial storage of eleven characters.
Thus, if eleven characters are entered before the send button is
depressed, the complete long distance telephone number is stored in the
registers 64, 67, 76 in the correct order. In the meantime, the counter 63
will
have counted up to "1011." The two lowest order stages of the counter 63 are
applied as direct inputs to the AND-gate 71. In addition, the highest order
stage
is applied as a direct input. However, the second highest stage is applied to
an
inverting input to the AND-gate 71, and the "send" signal is applied as a
fifth
input. Accordingly, when the counter holds the count "1011" and the send
button
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62 is depressed, the AND-gate 71 is fully enabled, and its output is applied
as
a first input to another AND-gate 72 which has a second input driven by the
dial
clock signal DCLK. The output of the AND-gate 72 is applied as a second input
to the AND-gate 73 whose first input is received from the single character
register 76. Thus, the eleven character long distance number is clocked
through
the AND-gate 73 and the OR-gate 69 to the modulation/demodulation circuitry
block 55 to be transmitted to the commercial service. When the call has been
completed, touching the end button 75 will serve to once again reset the
counter
63.
It has previously been noted that the local area code is semipermanently
stored in the three-character register 65. Because a cellular telephone is a
portable apparatus, it may be desirable, when it is physically moved to
another
area code, to enter the new area code into the three-character register 65 for
semi-permanent storage. This is readily achieved by depressing a program
button 75 which enables one input to an AND-gate 78 and entering the three-
character code from the keypad 61 which drives the other input to the AND-gate
78. The output from the AND-gate 78 is coupled to the three-character register
65 which thus receives the new area code for semi-permanent storage.
Those skilled in the art will appreciate that the apparatus shown in Fig. 3
is a synthesis of dialing procedures that can be controlled, as a practical
matter,
using a microcontroller which is a constituent of all modern cellular
telephones.
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Referring now to FIG. 4, such cellular telephones typically include a
microcontroller 81 with memory 82, an alphanumeric display 79 and various
input devices including keypad 61, send button, 62, end button 75, program
button 77, a menu access button 80 and additional buttons represented by the
button 83. Control outputs from the microcontroller 81 coordinate operations
among the keypad 61, control buttons 62, 75, 77, 80, 83, audio
circuits/devices
51, 52, 53, 54, modulation/demodulation circuitry 55 and duplex RF circuitry
56.
Accordingly, those skilled in the are will understand that the cellular
telephone
illustrated in FIG. 4 can be programmed to carry out the inventive functions
previously described with reference to FIG. 3.
FIG. 5 is a detailed flow chart which clearly sets forth the method of the
subject invention as it may be practiced in the exemplary cellular telephone
illustrated in FIG. 4. A call is instituted at step 84, and a determination is
made
at step 85 as to whether the presently stored local area code is correct. If
it is
correct, the Y path will be followed out of step 85. As a practical matter, if
the
presently stored local area code is incorrect, the caller will intervene,
using the
menu, display and programming facilities of the cellular telephone, to invoke
the
N path out of step 85 and store the correct local area code at step 86 such
that
the Y answer will then be followed through step 85 after the change.
Next, at steps 88 and 89, dialing is carried out until seven digits have
been dialed at which time, the Y path will be taken from step 88. Then, at
step
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89, if the "send" button is pushed within some suitable time (e.g., three
seconds), the Y path will be taken from step 90. (Another satisfactory
criteria for
step 90 is that if an eighth digit is promptly, e.g., within three seconds,
dialed, the
N path will be taken from step 90. The effect sought by any suitable process
is
to take the Y path if only seven digits are dialed before the "send" button is
actuated; if an eighth digit is dialed before the "send" button is actuated,
the N
path is taken from step 90.)
If the Y path is taken from step 90, the stored local area code is prefixed
to the dialed seven digits at step 94, and the ten digit local number is
transmitted
to the service at step 96 to complete the dialing procedure by which a ten
digit
local is transmitted by dialing only seven digits. When it is determined that
the
call has concluded at step 97, the "end" pushbutton is actuated at step 98 to
end
the call, step 99.
If, on the other hand, the N path is taken from step 90, at steps 91 and
92, dialing continues until eleven digits have been dialed at which time, the
Y
path will be taken from step 91. Once the "send" button is actuated at step
93,
the eleven digit (typically long distance) number is transmitted at step 95.
When
it is determined that the call has concluded at step 97, the "end" pushbutton
is
actuated at step 98 to end the call, step 99.
Thus, while the principles of the invention have now been made clear in
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an illustrative embodiment, there will be immediately obvious to those skilled
in
the art many modifications of structure, arrangements, proportions, the
elements, materials, and components, used in the practice of the invention
which
are particularly adapted for specific environments and operating requirements
without departing from those principles.
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