Note: Descriptions are shown in the official language in which they were submitted.
s
Automatic Call Routing De~ice
Technical Field
The present invention relates to a communications
system capable of handling bo~ voice and data. More
particularly, the present invention relates to a device for
routing incoming voice communications to a telephone set
and incoming data communications to a modem.
Background of the Invention
Communications systems have evolved from
simple voice transmission systems to present systems capable
of transmitting both voice and data. For many years,
common analog telephone sets have commw~icated with one
ano~er via telephone lines. As computers became available,
they also communicated with one another via the telephone
lines. In the beginning, the computers were complicated,
expensive devices limited in number with each computer
essentially enjoying a dedicated telephone line. However, as
~e populaAty of computers grew, a telephone modem was
cnnstructed allowing computers to communicate over
common telephone lines. A person having both a computer
and an telephone set can use each over the same telephone
line using the modem. Such an arrangement works very well
as long as the user uses either ~e telephone set or the modem
to transmit. Problems arise when the user's telephone set or
modem is to receive.
Basically, it must be determined whe~her an
incoming call is for the ~elephone set or for the modem.
When the modem answers an incoming voice call, the caller
may be greeted by a piercing and uncom~ortable modem
s answer tone. On the other hand, when the telephone set
answers an incoming data call, the incoming data may appear
as a strange variable modulation not recognizable by the
telepllone set as either an answer tone or a camer (i.e., a
human voice), resulting in the originator clearing the call.
0 This limits the usability of automatic answer modem
applications where voice calls come in on ~e same line as
data calls. One solution for this problem is to install separate
lines for the telephone set and for dle modem. A separate
line can be expensive and, depending on the resources of the
local telephone system, may not be available at any cos~.
Accordingly, it will be appreciated ~at it would be highly
desirable to provide a communications system wi~ a device
~or connecting both an analog telephone and a modem to a
single, common telephone line.
Summary o~ the Invention
The present invention is directed to overcoming the
problems set forth above. Briefly summari~ed, in
accordance with one aspect of the invention, a call routing
device connects a telephone set and a modem to a common
trunk line so that incoming calls from a calling party using a
remote modern are routed ~o the modem and incoming calls
from the calling party using a remote telephone set are
routed to the telephone set. The call routing device
comprises means for selectively placing a ringing sîgnal on
an extension line to the telephone set and means for placing a
ring back signal on the trunk line for the calling party.
Means are rcsponsive to a code from th5 calling party for
placing a ringing signal on an extension line to the modem
3s enabling a r~ng detector to answer connecting the modem to
the trunk line. Means are provided for granLting access to the
trunk line to ~lLe first of the telephone or modem to seize ~Le
tmLnk line and for blocking access to the trunk line to th
second of ~Le telephone set or modemL to seize the trunk line.
S According to another aspect of the present
invention, a methLod for connecting a telephone set and
modem to a common trunk line so thLat incoming calls from a
remote modennL are routed to the modem and incoming calls
from a remote telephone set are routed to thLe telephone set
lo comprises detecting an incoming r~nging signal over thLe
trunk line aLnd searching ~or a preselected caller code. ThLe
me~Lod also includes activating a ringing signal to the
mLodem in response to finding the preselected caller code,
responding to the ringing signal to thLe modem and detecting
an on-hook or an off-hook condition of the modem,
inhibiting the ring signal to the modem in response to
detecting aLn off-hook condition, connecting the modem to
thLe trunk line, det~cting an on-hook condition of thLe modemL,
and discoMLectiLnLg thLe modem from thLe trunk line in response
to detecting ~e on-hook condition of thLe modem.
ThLe present invention connects bothL an analog
telephone and a modem to a common telephone line so that
incoming calls from a modem are answered by thLe modem
and calls from a person are answered by the analog
telephLone. ThLe present invention prevents incoming voic
calls from being greeted by uncomfortable, sometimes
pierci.ng, modem answer tones, and prevents incoming data
calls from being greeted by voice signals.
It is an object of the present invention to connect
bo~h a modem and an analog telephone set to a common
telephone line. It is a feature of the invention that this object
is achieved by a call routing device having a first port
connected to the telephone line, a second port connected to
the telephone set, and a third port connected to the modem.
~5 Incoming calls over the telephone line from a remote
telephorle set are routed to the telephone set and incoming
calls from a remote modem are routed ~o the modem. An
advantage of the call routing device is that the call routing
device eliminates the need for sepa~ate lines for the modem
and telephone set the~by conservirlg resourees.
Another object of the present invention is to
facilitate outgoing calls over the common telephone line by
olle of the ~elephone set or modem without interference from
the o~er. ~his object is achieved by irnmediately connecting
0 the ~st of the telephone set and modem to go off-hook to the
telephone line and blocking access to ~he telephone
line to the second of the devices to go off-hook
blocking access to the second device to go off-
hook prevents inadvertent loss of transmis~ion.
Another object of the invenhon is to provide a call
routing device that interfaces with the modem and telephone
set in a simple manner without additional receptacles or
power extension cords. It is a fea~ure of the invention that
this olbject is accomplished by an AC current pass-through
jack provided on the automatic call routing device. Power is
suppliecl to the call routing device via a power cord
te~minated at the jack. The modem can receive its power
from the jack. An advantage provided by the jack is that
existing wiring can ~e used without the need for additional
recep~acles or extension cords.
Other aspects, objects, features and advantages of
the present invention will become apparent to those skilled
in the art upon reading the detailed description in
conjunction with the accompanying drawings and appended
claims.
Brief Description of the Drawings
Figure 1 is a simplified block diagram of a
preferred embodiment of a communications system
incQrporating a call routi~g device in accordance with the
.~
`'1'` ' ~
3~
present invention.
Figure 2 is a diagrammatic flow chart illustrating the
method implemented by the block diagram of Figure 1.
Detailed Description
Referring to Figure 1, an automatic call routing device
10 is depicted as a box 12 having an input port 14, a voice port
16, a data port 18, and an AC current pass-through jack 20. The
input jack 14 receives a common telephone or trunk line 22 over
which communications takes place between a remote party and a
local voice transmission device, such as a telephone set 24, or a
data transmission device, such as a modem 26. The voice device
24 is preferably connected to the voice jack 16 by a modular
connector or extension cable 28 and the data transmission device
26 is preferably connected to the data port 18 by a modulator
connector or extension cable 30. Power may be supplied to the
automatic call routing device 10 via a power cord 32 connected to
the jack 20. The modem 26 may receive its AC power from the jack
20. By this construction, the automatic call routing device 10
uses existing wiring without the need for additional receptacles
or extension cords.
The automatic call routing device 10 also includes a
tone detector, such as DTMF detector 34, ring detector 36, ring
generator 38, and ringback generator 39. The DTMF detector 34,
ring detector 36, ring generator 38, and ringback generator 39
are each connected to switching circuitry 40 and operate under
the direction of controller 42. The controller 42 is equipped
with a manually operated enable switch 44 for operator control.
The automatic call routing device 10 can be configured
; in a stand-alone form obtaining its power from either a separate
r~
b
,
, ', ~ ~'
- : , . '~
,
,.
pcwer supply connected by a cable or preferably from an integral
power supply 32 in which case the entire device preferably plugs
into an AC electrical receptacle.
When an incoming call is placed, an incoming ringing
signal is detected at the box 12 by a tone detector 33. The box
12 will answer the telephone line 22 and immediately send a
ringback signal to the caller over line 22. The caller does not
know that the box 12 has answered the telephone and continues to
wait for the telephone to be answered. The caller does not know
that the box 12 has answered the telephone because the caller
continues to hear the ringback signal indicating that the called
telephone is still ringing and has not been answered. The box 12
will insert a predetermined amount of silence, five to six
seconds for example, in the ringback signal. If the caller is a
modem, this silence will be detected as a silent answer. The
calling modem will respond by sending a DTMF tone. This DTMF
tone will be detected by tone detector 33 of the box 12 which
responds by generating a ring signal to the modem port 18. The
ringing signal from port 18 travels over line 30 to the modem 26.
When the modem 26 answers, the box 12 connects the modem 26 to
the incoming line 22 establishing a modem to modem link. Under
these conditions, a ringing signal is never sent out to the voice
jack 16 so the telephone set 24 does not ring.
If the DTMF tone is not detected after the quiet answer
time, then a ring signal to the analog telephone 24 is generated.
When the analog telephone 24 answers, the analog telephone 24 is
connected to the incominy line 22 establishing a voice link.
Under these conditions, the modem 26 does not receive a ring
signal.
p~
' ' ~' ' - - ,
, ' ~ ' '
- - ,
-
If either the modem 26 or telephone set 24 is not
answered and a calling station hangs up, the box 12
discontinues the ring sigrlal. An absence of ring voltage on
incoming line 22 for about five seconds or more indicates the
s calling station has hung up. After a connectiorl is established,
it is disconnected after the modem 26 or the analog telephone
24 hangs up. If, during a voice call or a data call, the
unselected device goes off-hook, a fast busy tone is received.
The apparatus illustrated in Figure 1 implemen~s a
0 method for connecting a ~elephone set 24 and a modem 26 to
a common trunk line 22 so ~at incoming calls from a remote
modem are routed to the modem 26 and incoming calls from
a remo~e telephone are routed to the telephone set 24. The
method includes detecting an incoming ringing signal over
lS the trunk line 22 using ring detector 36s searching for a
preselected caller code, activating a ringing signal to the
modem 26 in response to finding the preselected caller code,
responding to the ringing signal to the modem 26 and
deteeting an on-hook or aIl off-hook condition of the
modem, inhibiting the ringing signal to the modem 26 in
response to detecting the of~-hoo~ condition, connecting the
modem 26 to the trunk line 22, detecting an on-hook
condition of ~e modem 26, and disconnecting the modem 26
from ~e tIunk line 22 in response to detecting the on-hook
condition of the modem. The method further includes
stopping the ringing signal to the modem 26 after a
predetermined time if the modem 26 is in an on-hook
condition.
Figure 2 is a general flow chart diagram of the
method whereby the objects of the present invention may be
accomplished by the disclosed apparatus. Those skilled in ~e
art will understand how to program the controller 42 to
accomplish the steps disclosed. It will be understood by those
skilled in the art that the flow chart represents a possible
series of steps ~at may be taken to accomplish ~e objectives
of the present invention, and that other sequences of steps
may be employed with success in accomplishing the
connecting of ~e incoming line 22 to ~e telephone set 24 and
modem 26 on a selective bæis.
S Starting at 50 in the flow chart of Figure 2, a
calling party initiates either a voice call or a data call over the
telephone line 22 (Figure 1). As is known in the art, a calling
party dials the number of the called party with the called
party being signalled by a ringing signal over the telephone
0 line. rrhus, at S2 the automatic call routing device 10 detects
the presence of the incoming ringing signal.
At decision block 54, the automatic call rou~ing
device decides whether the ringing signal is from a voice
source, such as a telephone set, or a data source, such as a
modem. Thus, at decision block 54 the switching circuitry
40 checks for the presence of a caller code.
At 52, when an incoming call is placed, the ring
signal is detected at the box 12. The box will answer the
telephone line 22 and immediately send a ringback signal to
the caller. The caller does not know that the box 12 has
- answered the telephone and the caller continues to wait for
~e called telephone to be answered. The box will insert a
five to six second silence in the ringback signal. If the caller
is a modem, this silence will be detected as a silent answer
2S and th~e calling modem will send a preselected DTMF tone.
This I)TMF tone will be detected by the box 12. When the
tone is detected, the box will generate a ring signal to the
modem port 18. At 54, a yes answer to the question "did
caller send the code?" indicates ~at the tone is detected and
the box will generate a ring signal to the modem port 18.
When the modem 26 answers, the box 12 connects the
modem 26 to the telephone line 22. If ~e modem does not
answer, ~e ringing signal is stopped after a preselected time
interval.
At the star~ 50, for incoming calls, no connection
- ',.
3~3~
exists to either the modem 26 or telephone set 24 initiallyO
When ring voltage comes over the telephone line 22, the call
routing device 10 goes off-hook producing a distinctive
ringback tone on the telephone line 22. This nngback tone is
s followed by a ~ive to six second interval of silence. If the
incorning call is from a remote modem that is waiting for a
silent interval, ~is silent interval of approximately five ~o six
seconds is sufficient to break the remote modem out of its
waiting state causing it to continue with the dial command
string. A new modem could also be programmed to detect
the distinctive ringback tone to break it out of the waiting
mode immediately without waiting for ~he quiet interval. An
incoming caller desiring to connect to the modem would
enter a particular DTMF tone during ~e silent period. The
toIle may be a single DTMF tone or any valid DTMF tone or
a series of DTMF tones to provide a security barrier for
modem access.
Thus, a calling modem can respond to the ringback
tone or to a quiet interval depending upon the type of calling
modem being used. As an example, a manual dial modem
(acoustic coupler) wi~ a human operator could connect by
listening for the distinctive ringback and manually pressing
the required DTMF tones. A call originator on a pulse-only
central office could switch to tones to enter the modem
selection code. At 56, when the modem select is received
within t~he required time, the call routlng device 10 generates
ring voltage to the modem jack 18 and ringback tone to the
line jack 14 in a normal cadence until the modem 2S answers.
At decision block 58, when the modem 26 goes off-hook, the
incoming telephone line 22 is connected to the modem 26 and
the modem proceeds normally, generating an answer tone
and so forth.
At block 60, ~e call routing apparatus 10 detects
the of~-hook condition of the modem indicating dlat ~he
modem is answesing the call. At 62, the apparatus inhibits
- .
,: :
., ' ' , : ~
V
the ring signal because the ring signal is no longer needed once
the modem answers the call. The answer tone generated by the
modem lets the calling party know that the modem has answered.
Block 64 indicates that the modem 26 is connected to the incoming
line 22 that in turn is connected to the jack 14, switching
circuitry 40, modem jack 18 and modem line 30 to the modem 26.
Block 66 represents the exchange of data between the
calling modem and the called modem. Block 68 indicates that the
call routing apparatus 10 monitors for when the modem 26 hangs
up, and hangs up the incoming telephone line circuitry
simultaneously, returning to an idle state. When the modem 26
returns to an on-hook condition, the device interprets the on-
hook condition as the end of the data exchange.
At decision block 54, if the calling party does not send
a modem select tone, the automatic call routing device rings the
telephone set 24 and sends a ringback tone out on the telephone
line 22 as indicated at 70. At decision block 72, as with
decision block 58, the automatic call routing device will
automatically hang up after a predetermined interval of time if
there is no answer by the called device. If the called telephone
set is answered 61, the ring signal is stopped 63 and the
telephone set 24 is connected 65 to the incoming line 22. The
telephone conversation can now take place 67 and the call routing
device will monitor the conversation to terminate 69 connections
when the conversation has ended.
In addition to having a modem select code, it may
be desirable to have a telephone select code also. This is
because there may be a delay of up to approximately eight
seconds between when the call routing apparatus answers and when
it starts rings the called telephone. Callers who do not
wait for the four to five rings would hang up too soon.
This situation could be overcome by also having a telephone
select code that could be shared with the frequent callers that
, .
would cause the telephone to start ringing immediately,
resulting in only a two to three second total delay.
Operation of the call routing device is such that
going o~f-hook on one of the ports 16, 18 results in that port
s being immediately coMected to the telephone line 22. Going
on-hook disconnects the telephone line 22. To reduce
interference by the other device, going of~-hook with the
second device does not connect it imrnediately to the line.
Initially9 incoming sounds could be monitored, but no
0 outgoing signals would be allowed to interfere with the
activity of the other pOlt. If the originally connected port
went on-hook, the second device would be connected to the
telephone line resulting in a switch of a call to the other port.
~f the original port were to go baclc off-hook, it will be
treated as a secondary, monitoring device. This allows
voiçe/data switching to take place pretty much as it does now,
but provides the added benefit of reducing inadverten~
interruption of calls in progress.
While the call routing device 10 has been described
thus far as a stand-alone~ device, it could easily be
incorporated into a modern. Incorporation of ~e device 10
into a modem would permit other enhancements as well, such
as software control to set the DTMF codes expected, or to
enable or disable the switching feature entirely. The device
2s could be powered from the modem power supply and use the
existin~ telephone line jack and extension jacks for
connection. Some of ~e logic could be implemented in the
circuits now present in a modem, such as DTMF generation,
for example, and the power off pass-~rough relay. Some
circuitry such as DTl~F detecting and ring generation
circuitry could be added. Operation of the circuitIy could be
a little bit different when imbedded in the modem. If the
modem was in an autoanswer mode for example, receipt of
the modem select tone could result in the modem going
immediately off-hoolc and answering with no need to
12
actually generate ring voltage. The nng would be generated
normally when ~he modem is not in the automatic answer
mode, generating ring messages and allowing s~ftware to
explicitly answer by a command issued to ~e modem.
s The stand-alone device would have a switch or
button tpower switch and LED indicator) to disable it and
change it into a straight Y-çonnector. The in-modem
implementation could be enabled/disabled by a command and
~e default would be disabled for compatibility with current
modems. I~e modem implementation could also have a
command to set the modem select code. The select code
could be useful as a secur~ty feature.
Voice generation could also be used to instruct the
incoming caller what buttons to press to connect to the
telephone or to the modem. Incoming DTMF tones during
this message would be accepted and acted upon, terminating
the message if possible. The rnessage could be preceded by
the distinctive ringback to allow immediate break~rough for
modems that can respond to it. The message could also be
followed by six seconds of silence to trigger modems waiting
for the silence. A record function could be put in the
apparatus to allow the user to record a message (stored
compressed in EEROM/EAROM~, or ROM cartridges could
be used for ~e message that could be repla~ed by the user.
2s It will now be appreciated that there has been
presente:d a call routing device ~or connecting both an analog
telephone and a modem to a common telephone line so that
incoming calls from a modem are answered by the modem
and calls from a person are answered by the analog
telephone. The device is essentially a box with ~ree ports.
One port is connected to ~e telephone line, one port is
connected to the modem, and the ~ird port is connected to an
analog telephone. When an incoming call is placed, the ring
signal is detected at the box. The box will answer the
3s telephone line and immediately send a nngback signal to the
13
caller. The caller does not know the bQx has answered the
telephone and continues to wait for the telephone to be
answered. The box will insert a five to six second silence in
the rin~baclc signal. If the caller is a modem, this silence
s would be detected as a silent answer. At ~his time, the calling
modem will dial Oll DTMF tolle. This DTMF tone would be
detected by dle box and the box will generate a ring signal to
the modem port. When the modem answers, ~he box
connects the modem to the telephone line.
If ~he DTMF or any other predetermined tone is
not detected after dle quiet answer time, then a ring signal to
~he analog telephone is generated. When the analog
telephone answers, then the analo~ ~elephone is cormected.
ï he modem does not receive a ring signal for this case and
the analog line does not ring when the modem code is
present. If either the modem or telephone is not answered
and the calling station hangs up, the call routing device
discontinues the ring signal. After a connection is
established, it is disconnected after the modem or the analog
telephone hangs up. If during a voice call or a data call, the
unselected port is taken off-hook, a fast busy tone is
received.
While the invention has been described with
reference to a preferred embodirnent, it will be understood
2s by those skilled i~ the art that various changes may be made
and equivalents may be substituted for elements thereof
without departing from the true spirit and scope of the
invention. In addition, many modifications may be made to
adapt a particular situation and material to the teachings of
the invention without departing from the central teachings of
the present inYention. Therefore, the present
invention is to be limited only by the claims
below.
