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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communications switch system and, more
particularly, to such a switch system that includes a call originator unit
and a call receiver unit in order to implement a telephone line
consolidation.
2. Description of the Prior Art
In the present local telephone switching devices, Touch (DTMF) Tones are
used to provide call directions. Heretofore, there have been several
drawbacks associated with the use of such tones. For example, the call
originating device is typically unable to determine when the call
receiving instrument has been connected and, therefore, cannot detect when
to transmit call direction tones. Further, the call originating device
typically cannot determine when the call receiving instrument has received
the direction or selection tone.
Another drawback or disadvantage is that the call originating device must
transmit the call direction tone within a very short time period. This
time period starts when the receiving switch device is ready to detect the
tone and ends just before the call is directed to a default device. The
starting time of this period will vary. Specifically, the starting time of
the time period is affected by the time it takes for a telephone call to
traverse the originating caller's telephone central office, the long
distance network, and the receiving caller's central office. Depending on
the distance between the calling instrument and the call receiving
instrument, one, two or all three of these delays may be interposed. The
problem arises from the fact that the calling instrument, not knowing when
the receiving switch device is ready to accept tones, must delay for the
worst case connection time period, in addition to the detection time
period. This long worst case delay will cause additional billable
telephone time to the customer, and further, if it is too long, it may
extend beyond the end of the detection time period causing the call
receiving instrument to connect to the incorrect device. This would
require another call attempt by the calling instrument also increasing
telephone expense.
A further disadvantage is that if the calling instrument is automated, it
typically has a limited ability to transmit the selection tones or to
detect the results of the switch function. Accordingly, the incoming call
can be lost.
A still further disadvantage is that the software for the calling
instrument or device, such as a computer, may not have the capability of
handling the number of characters that are needed to preprogram the long
delays and the direction tones. Therefore, changes are required in
existing software of the computer to insert sufficient pauses to ensure
that any telephone line consolidation device has answered before the
direction tone is sent. Also, the pauses will occur on the telephone line
and, therefore, at the telephone caller's expense.
Accordingly, there has, heretofore, been a need for a communication system
or device that interfaces with the calling instrument and an incoming
telephone line having a receiving instrument and that uses the pulse or
Touch (DTMF) Tones received from the calling instrument to direct the call
to the receiving instrument. Further, such a communication device can be
used without changes required in the originating device's software and
without additional use of the telephone line. Still further, such a system
needs to act within a very brief time period.
Furthermore, a need exists to cascade receiving switches to modularly
increase the number of devices that can be addressed. This requires
advanced abilities to transmit selection tones that include appropriate
acknowledgment signals.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a switch system.
It is another object of the present invention to provide such a switch
system that permits a calling instrument to direct an incoming call to a
receiving instrument that shares a telephone line, without requiring any
interaction from the calling or the receiving instruments.
It is still another object of the present invention to provide such a
switch system that includes a call originator unit and a call receiver
unit.
It is yet another object of the present invention to provide such a switch
system that directs a call from a calling instrument to a receiving
instrument and comprises a call originator unit that is electrically
connected between the calling instrument and an outgoing telephone line
and a call receiver unit that is electrically connected between an
incoming telephone line that is electrically connected to the outgoing
telephone line and the call receiving instrument.
These and other objects are provided for by a switch system for directing a
call from a calling instrument to a receiving instrument. The switch
system comprises a modem identifier unit electrically connected between
the calling instrument and an outgoing telephone line. The modem
identifier unit includes means for detecting the call from the calling
instrument, means for operatively connecting the calling instrument to the
outgoing telephone line, means for detecting whether a line selection is
enabled and means, in response to the line selection enabled detecting
means,. for transmitting a valid line selection tone. The switch system
also comprises a call receiver unit electrically connected between an
incoming telephone line electrically connected to the outgoing telephone
line and a call receiving instrument. The call receiver unit including
means for detecting the call, means for initiating an internal line
selection detection mechanism that includes means for detecting whether
the valid line selection tone is detected and means for determining that
no line selection tone has been detected within a fixed amount of time.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and still other objects and advantages of the present
invention will be more apparent from the following detailed explanation of
the preferred embodiments of the invention in connection with the
accompanying drawings wherein:
FIG. 1 is a block diagram of the switch system of the present invention;
FIG. 2 is a flow chart of the operation of the originator unit of the
switch system of the present invention;
FIG. 3 is a flow chart of the operation of the receiver unit of the switch
system of the present invention;
FIG. 4 is the logic of the line selection timing for the automated line
select mode embodiment of the switch system of the present invention;
FIG. 5 is the logic of the line selection timing for the over-ride mode
embodiment of the switch system of the present invention;
FIG. 6 is the logic of the line selection for another embodiment of the
receiving unit of the switch system of the present invention; and
FIG. 7 is a block diagram of the interaction of components of the call
receiver unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings and, in particular, FIG. 1, there is provided a
switch system generally represented by reference numeral 1. The switch
system 1 allows a calling instrument or device 4 to direct a telephone
call to a call receiving instrument 6, that may or may not share an
internal telephone line 8, without the elements of the switch system
disrupting or interfering with the telephone call. The switch system 1
includes a call originator unit 10 and a call receiver unit 20.
The call originator unit 10 is a modem identifier unit or device ("MID").
The modem identifier unit 10 is electrically connected at point 12 to at
least one internal telephone line and jack 14. The internal telephone line
and jack 14 are used to connect electrically, and also physically, the
calling instrument 4 to the modem identifier unit 10. The modem identifier
unit 10 is also electrically connected at point 16 to an outgoing and,
preferably, external telephone line 18.
The modem identifier unit 10 has certain detection capabilities as will be
defined below. In addition, the modem identifier unit 10 can be configured
to transmit line selection tones or, alternatively, an override mode will
prevent the transmission of the line selection tones. When the modem
identifier unit 10 has been configured by the user to transmit line
selection tones, it does so at the appropriate times and until the modem
identifier unit detects an acknowledgment tone back from the call receiver
unit 20. Whether or not the modem identifier unit 10 has the ability to
transmit line selection tones is determined by one of three different
operating modes, namely by its physical connection to the calling
instrument 4, the pre-programming of line selection tones and the
transmission of a line selection over-ride tone by the calling instrument
during the dialing sequence. In other words, the modem identifier unit 10
does transmit line selection tones if the modem identifier unit tone
transmission for the unit and the particular connection port are both
enabled and a default selection tone has been selected for the particular
modem identifier unit connection port or the presence of an override tone
or tones is detected in the dialing sequence generated by the calling
instrument 4. If a default selection tone has been selected, and an
override tone is detected, the override tone takes precedence. Also, an
override tone might prevent a selection tone from being transmitted for a
port that had a default tone enabled. The feature of a line selection
override tone allows communications to be made through the modem
identifier unit 10 without transmitting the line selection to locations
that do not include a call receiver unit 20.
A preferred modem identifier unit 10, preferably, is a desktop unit that
includes at least four jacks. In a preferred embodiment, the jacks are
positioned in the rear of the unit. One jack is for the telephone line,
while the remaining three jacks are for the devices of the internal
telephone system. The modem identifier unit 10 may also include
indicators, such as LED indicators, to advise the user of the configured
option and to display the progress of the telephone call.
The call receiver unit 20 is known as a call receiver (RCVR) unit. It
interfaces with a telephone line 19 and with the receiving instrument 6.
The receiving instrument 6, like the calling instrument 4, is an internal
telephone device. The internal telephone device may include one or more of
the following devices, namely a telephone, facsimile machine, point of
sale machine, computer modem or an alarm monitoring system. The internal
telephone system may also include analogous modems and the like.
The call receiver unit 20 is electrically connected to the external
telephone line 19 at point 26 and to at least one internal telephone line
at jack 28 or port C2. The receiving instrument 6 is electrically
connected to jack 28.
The function of the call receiver unit 20 is to receive incoming calls,
determine which of the receiving devices the telephone call is intended
for, regenerate the ring on the appropriate device port 28, detect the
receiving device going off-hook in response to the ring signal, and
finally connecting the call through, from the receiving unit 6 to the
telephone company line 19.
U.S. application Ser. No. 07/384,772, filed Jul. 25, 1989, now U.S. Pat.
No. 5,056,132, which issued on Oct. 8, 1991, which is owned by the
assignee of the present application, describes how the call receiver unit
20 functions except that the present unit is also capable of acknowledging
receipt of selection tones to the caller by responding with an
acknowledgment tone. U.S. Pat. No. 5,056,132, which is incorporated herein
by reference, provides that the call receiver unit 20 has the ability to
detect and distinguish different DTMF tones from an incoming caller for
the purpose of directing the call to the appropriate device port.
Furthermore, the call receiver unit 20 has a programmable default port, to
which incoming calls are directed if no other indication is received.
Finally, the receiver unit 20 as described in U.S. Pat. No. 5,056,132 has
the ability to generate digitized voice messages (or any other audible
prompt) to greet, and/or direct incoming callers while the device is
attempting to detect a direction tone.
The call receiver unit 20 may be programmed to enable or disable the
transmission of the acknowledgment tone depending on the device selected.
This programmability eliminates the transmission of acknowledgment for
devices that are typically selected by non-modem identifier callers, such
as, for example, normal voice telephone calls. The programmability is
obtained locally by putting the receiver unit 20 into a "program mode" and
programming with DTMF tones generated by a locally connected telephone.
Alternatively, the receiver unit 20 can be programmed by a remote computer
via DTMF tones. Remote programming is protected by an algorithm based
password system so that an unauthorized caller cannot reconfigure remote
receiver units.
FIG. 2 is a flow chart of the logic for the operation of the modem
identifier unit 10. The modem identifier unit 10 is initiated by detection
of the calling instrument going to its "off-hook" or operative condition.
Accordingly, the modem identifier unit 10 includes a first detector to
detect the operative condition of the calling instrument. In a preferred
embodiment, the first detector, as shown by block 30, detects that the
calling instrument is prepared to send an outgoing communication. After
the modem identifier unit 10 detects (Yes in FIG. 2) the operative
condition of the calling instrument, the calling instrument is operatively
connected to the outgoing telephone line as shown by block 32.
The modem identifier unit 10 determines, as shown at block 34, whether the
calling instrument is connected to an internal jack that provides for
automated line selection. If the calling instrument is so connected, the
modem identifier unit 10 will load the programmable default line select
code or tone (block 36) for that jack. In addition, the modem identifier
unit 10 will commence detection 38 of the DTMF (or touch) tones. If the
calling instrument is not connected to an internal jack that provides for
automated line selection, the telephone call will be directed to a
connected line state 35 where it shall remain until the calling instrument
hangs up or goes "on-hook" as shown by block 58.
The modem identifier unit 10 includes elements that implement the override
tone feature, as shown by blocks 40, 42 and 44. In step 40, a first
determinator determines whether a first time period of x seconds or
greater has elapsed after detection of the last DTMF tone dialed by the
calling instrument. If the answer is no or if it has not been determined,
means 40 is reactivated. If the answer is yes, the modem identifier unit
10 determines by a second determining device, as shown by block 42,
whether an over-ride dial or instruction has been detected. If no
over-ride instruction has been detected and if a detector device, as shown
by block 44, detects that a second time period of y seconds has elapsed
since the last code without another tone being detected, the modem
identifier unit 10 will determine, as shown by block 46, whether a valid
line selection is still loaded and enabled and, if so, will commence
transmission of the port selection tones to the dialed call receiver unit.
If the line selection code is invalid or has been disabled by an override
code, then no selection codes will be transmitted, and the modem
identifier unit 10 will wait in the line connect state, block 35, for the
calling instrument to hang up, or go "on hook" as detected in as shown by
block 58. In the FIG. 4 embodiment, the value of the default line or port
selection tone is equal to the port on the modem identifier unit 10 at
which the calling instrument is connected. For example, if the calling
instrument is connected to port C1 of the modem identifier unit 10, the
default selection tone will be such that a connection will be made to the
device on port C1 on the dialed call receiver unit 20.
The modem identifier unit 10 can be programmed so that the values of x and
y can be made to be any period of time between about 0.5 and about 10
seconds. It is preferred that the value of x be about 1.5 seconds and the
value of y be about 1.5 seconds. The values of both "x" and "y" are
selected to be greater than the standard modem delay character (1 second),
but less than two delay widths to speed the dialing process. These values
are selected so that the calling instrument has ample pause time (x=y=1.5
seconds) between digits dialed on the outgoing call without triggering the
default code selection. Furthermore, the sum of x+y should be kept less
than the minimum time expected to complete a telephone call to keep the
override specifier tones from being detected by the RCVR unit.
Referring back to FIG. 2, after it is affirmed that the line selection is
enabled, the transmit code is set to a first stored code as shown in block
48. The code is then transmitted periodically by a transmitter, as shown
by block 50, and after acknowledgment is received by a receiver, as shown
by block 52, the next code is obtained, as shown by block 54, and
transmitted. This is repeated until all of the codes are obtained and
transmitted, see block 56. As a safety against an undetected port
selection tone, or an undetected acknowledgment tone, a limit detector, as
shown by block 49 is provided to allow the selection tones to "time out"
after the re-transmit limit has been reached. In this way, the telephone
line will not be held open an unnecessary length of time. At that time, a
off-line detector, as shown by block 58, detects when the calling
instrument has hung-up or moved to its inoperative condition and,
therefore, service is disconnected as shown in 60.
If after the first code is transmitted by the transmitter, as shown by
block 50, and an acknowledgment tone is not received by the receiver, as
shown by block 52, it is then determined, as shown by block 54, whether n
seconds has elapsed. If n seconds has elapsed, the telephone call or modem
identifier unit's logic reenters means 50. If n seconds does not elapse,
the modem identifier unit will reenter an acknowledgment detection mode by
the receiver shown by block 52. The modem identifier unit 10 can be
programmed at production time so that n seconds can be any number of
seconds from about 0.1 to about 5.
The operation of the call receiver unit 20 is illustrated in FIG. 3. The
call receiver unit 20, upon detection of an incoming call by a detector,
as shown by block 61, "picks up" the call and initiates, as shown by block
62, the internal line selection detection mechanism. This line selection
detection mechanism includes a detector, as shown by block 64, for
detecting whether a valid line selection tone is detected. The detector 64
also detects a device tone over the communications medium, such as, for
example, a CNG tone for fax machines or a carrier tone for modems. The
line selection a determiner, as shown by block 66, also includes means 66
that determines that no tone has been detected within a fixed amount of
time.
If the detector shown by block 64 determines that no valid selection code
has been detected, then the determiner shown by block 66 determines if the
line selection time has expired. If it has not expired, the modem
identifier unit logic and the telephone call are returned to the detector
64. If no valid selection is detected by the detector 64 and the line
selection time has expired as determined by the determiner 66, the modem
identifier unit's logic moves to a selector, as shown by block 68, to
determine whether to select a default device. If means 64 determines that
a valid selection code has been detected, the call receiver unit's logic
continues, as shown by block 70, to determine whether the selected
internal line has been programmed to provide an acknowledgment means for
transmitting an acknowledgment instruction or tone. If an acknowledgment
means is enabled, an acknowledgment tone is transmitted by a transmitter,
as shown by block 72, over the communications medium to the caller such
means for transmitting the acknowledgement tone is depicted as block 200
in FIG. 7. The internal receiving instrument is then notified by a
notifier, as shown by block 74, of the communication and connected by a
connection device, as shown by block 76, to the external telephone line.
The call receiver unit 20 then waits to detect that the receiving
instrument 6 has been "hung up" at which time it disconnects the telephone
line and idles waiting for the next action.
The use of the acknowledgment tone or signal allows the transmission of
selection tones to be terminated as soon as the call receiver unit 20
detects the first tone as shown in FIG. 4.
If line selection feature is still enabled after the completion of the
dialing and the time provided for the over-ride tone detection, the modem
identifier unit 10 will commence transmitting line selection tones. These
line selection tones are transmitted every w seconds for up to z seconds
or until an acknowledgment tone is detected from the call receiver unit
20. Once the acknowledgment tone is detected by the modem identifier unit
10, the modem identifier unit waits to detect that the calling instrument
4 has gone "on hook" (e.g. hang up) or its non-operating condition. At
this time, the electrical connection is released and the modem identifier
unit 10 is in its idle mode in which it waits for the next call. As with
other time periods in the modem identifier unit, the w and z seconds for
the line selection tone can be programmed at production time.
FIG. 5 is directed to an alternative embodiment in which it is necessary to
direct a call to a non-standard port or to instruct the modem identifier
unit 10 to send no direction tones. This situation might occur if a call
receiving instrument 6 has not been installed. Accordingly, for these
situations, an over-ride capability is needed. Referring to FIG. 2, DTMF
tones detected after dialing by the calling instrument is complete and
before an over-ride detection period of length y seconds are considered to
be line selection override tones, see blocks 42, 80. The over-ride tones
by means 82, 84, 86 and 88 over-ride elements, as shown by blocks 82, 84,
86 and 88 of FIG. 2, replace the default loaded line selection tone.
Alternately, a special tone can disable the line selection feature for the
current call. After detecting an over-ride tone, the call progresses as in
the automated selection mode, however the over-ride tone or tones is/are
substituted for the default selection tone.
As shown in FIG. 6, the use of acknowledgment tones allows several call
receiver units 20 to be cascaded. This cascading permits the use of more
internal telephone devices at the receiving instrument on the same
telephone line. Without acknowledgment tones, the modem identifier unit 10
would be unable to determine when the primary call receiver unit has
received the first line selection tone and, thus, would be unable to
reliably transmit the line selection tones for the secondary, tertiary and
other call receiver units at the appropriate times.
The cascaded call receiver units 20 attached to the primary call receiver
unit or a subsequent call receiver unit can be accessed by the "over-ride"
method or by pre-programmed default line selection codes. For example, an
over-ride code of "23" would access a secondary call receiver unit
attached to port C2 of the primary call receiver unit, and ring port C3 of
the secondary call receiver unit. In the calling sequence, once an
acknowledgment is received for connection through the primary call
receiver unit, the modem identifier unit 10 begins transmitting the
secondary line select tone in the same manner. When all line select tones
have been transmitted, the modem identifier unit 10 waits to detect that
the calling instrument 4 has completed the call by the "hang up" of the
calling instrument.
The modem identifier unit 10 may also act separately as a call receiver
unit 20. The modem identifier unit is primarily intended to handle
outgoing calls. However, it may also been designed to deal with incoming
calls in the same way as a call receiver unit. For example, if a modem
identifier unit is used primarily to connect to port C3 devices in the
remote sites, the transmitting computer would be attached to port C3. A
telephone could be connected to port C1, and port C1 would be programmed
as the default port for incoming calls. Using these connections, a single
telephone line to be used for computer room voice telephone access and
routine data polling calls. The modem identifier unit, at present, does
not have the ability to acknowledge incoming modem identifier tones or to
be remotely reconfigured as normal receivers would be. However, these
features can be incorporated therein. The modem identifier unit when used
as a receiver will acknowledge incoming tones and will have the ability to
be remotely configured the call receiver unit 20 is illustrated in more
detail in FIG. 3 of U.S. Pat. No. 5,056,132 that has already been
incorporated herein by reference. FIG. 7 herein is a block diagram of the
interaction of the components of the call receiver unit 20, and this FIG.
7 shows a device essentially identical to the switch device or call
receiver unit of FIG. 3 of U.S. Pat. No. 5,056,132.
The present switch system has many advantages since the calling instrument
is not required to transmit any line selection tones, or perform any
actions as part of the switching system. Further, the transmission of line
selection tones continues only until the call receiver unit receives the
communication and detects the line selection tone. This results in a
savings of communications time and cost to the caller. In addition, this
method allows multiple call receiver units to be cascaded, each requiring
a line selection tone to "route" the communication. The modem identifier
unit can detect each call receiver unit in order and transmit the
necessary line selection tone for the unit thus providing the ability to
share a single telephone line amongst a large number of internal telephone
devices, and making it implementable in a modular fashion.
It has been found that by the use of the preferred embodiment of the
present invention/that the normal delay added by the switch system is
reduced to less than one second. It is believed that connecting a normal
telephone call would take anywhere between five to twenty-five seconds.
Accordingly, the software to reliably connect the normal telephone call
using other switch devices would need to wait for at least the twenty-five
seconds. Therefore, the telephone time used by the consumer is
dramatically reduced by the use of the present switch system. This in turn
reduces the consumer's telephone cost.
The present invention may, of course, be carried out in other specific ways
than those set forth herein without departing from the spirit and
essential characteristics of the present invention. The present
embodiments are, therefore, to be considered in all respects as
illustrative and not restrictive, and to provide for all changes coming
within the meaning and equivalency range the appended claims are intended
to embrace.
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