CA1283230C - Automatic call routing device - Google Patents

Abstract

Automatic Call Routing Device Abstract A call routing device connects a telephone set and a modem to a common line so that incoming calls from a modem are routed to the modem and incoming cells from a telephone set are routed to the telephone set. The call routing device selectively places a ringing signal on an extension line to the telephone set and places a lingback signal on the telephone line for the calling party. The call routing device is responsive to a code from the calling party for placing a ringing signal on an extension line to the modem enabling a ring detector to answer, connecting the modem to the line. The call routing device grants access to the first of the telephone set and modem to seize the telephone line and blocks access to the second one to seize the trunk line.

Description

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 .~
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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~
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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.
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' ' ~' ' - - , , ' ~ ' ' - - , -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 - ',.

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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 - .
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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 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 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.

Claims (11)

1. A call routing device for connecting a selected one of a local telephone set and a local modem to a common trunk line so that an incoming call from a calling party who is using a remote modem is routed to said local modem and an incoming call from said calling party who is using a remote telephone set is routed to said local telephone set, comprising:
ring detector means for detecting an incoming ringing signal on said common trunk line;
switching means for answering said incoming call and connecting a selected one of said local telephone set and said local modem to said common trunk line;
ring generator means for selectively placing a ringing signal on an extension line to said local telephone set or an extension line to said local modem;
ringback generator means for placing a ringback signal on said common trunk line to said calling party;
tone detector means for detecting a predetermined tone placed on said common trunk line by said calling party, control means responsive to detection of said incoming ringing signal for causing said switching means to answer said incoming call, responsive to detection of said predetermined tone for causing said ring generator means to place said ringing signal on said extension line to said local modem, responsive to said local modem going off-hook for deactivating said ring generator means and causing said switching means to connect said local modem to said common trunk line, and responsive to a lack of detection of said predetermined tone for activating said ringback generator means and causing said ring generator means to place said ringing signal on said extension line to said local telephone, set, and responsive to detection of said local telephone set going off-hook for deactivating said ringback generator means and said ring generator means and causing said switching means to connect said local telephone set to said common trunk line.

2. The call routing device of claim 1 and further comprising means for determining whether said local modem is in an on-hook condition or an off-hook condition.

3. The call routing device of claim 1 wherein said control means inhibits said ringing signal to said local modem after a predetermined time if said local modem remains in an on-hook condition.

4. The call routing device of claim 1 wherein said control means causes said switching means to disconnect said local modem from said common trunk line in response to said control means detecting an on-hook condition subsequent to detecting an off-hook condition.

5. The call routing device of claim 1 and further comprising means for granting access to said common trunk line to a first of said local telephone set and said local modem to seize said common trunk line and blocking access to said common trunk line to a second of said local telephone set and said local modem to seize said common trunk line.

6. The call routing device of claim 1 wherein said control means activates said ringback generator means for a first predetermined period after said answer of said incoming call and subsequently deactivates said ringback generator means for a second predetermined period.

7. A method for connecting a selected one of a local telephone set and a local modem to a common trunk line so that an incoming call from a remote modem is routed to said local modem and an incoming call from a remote telephone set is routed to said local telephone set, comprising the steps of:
detecting an incoming ringing signal on said common trunk line;
answering said incoming calls;
monitoring said common trunk line for a predetermined tone;
responding to said predetermined tone by activating a ringing signal on said extension line to said local modem and responding to said local modem going off-hook by inhibiting said ringing signal to said local modem and connecting said local modem to said common trunk line; and responding to a lack of said predetermined tone by placing a ringback signal on said common trunk line, placing a ringing signal on said extension line to said local telephone set and responding to said local telephone set going off-hook by terminating said ringing signal and connecting said local telephone set to said common trunk line.

8. A method according to claim 7 and further comprising the step of stopping said ringing signal to said local modem after a predetermined time if said local modem is in an on-hook condition.

9. A method according to claim 7 including granting access to said common trunk line to a first one of said local telephone set and said local modem to seize said common trunk line.

10. A method according to claim 7 including blocking access to said common trunk line to a second one of said local telephone set and said local modem to seize said common trunk line.

11. The method of claim 7 and further comprising the steps of:
placing said ringback signal on said common trunk line for a first predetermined period after said answering of said incoming call; and subsequently inhibiting said ringback signal for a second predetermined period.