Abstract:
A call controlling apparatus for receiving input signals each including a phone number through respective communication channels and making a call. The apparatus provides a plurality of telephones corresponding respectively to the channels and a storage storing respective phone numbers of the telephones; detects the phone number in the input signals; determines in which input signals the phone number is detected; selects the phone number based on the determining; compares the selected phone number with those stored in the storage and makes the call on the corresponding telephone depending on a result of the comparison.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a call controlling apparatus and method used for an order-wire system which helps improve reliability and maintainability of a communication system. 
     In wire and radio transmission systems using the SDH (Synchronous Digital Hierarchy) transmission method, for example, a communication channel for the order-wire system is provided between terminal equipment for exchanging maintenance information and so on, through the channel, in order for maintenance personnel to mutually exchange maintenance information, for example. The communication-channel information is transmitted multiplexed with user information or a payload. 
     There are two types of channels for the order-wire system: a channel available only between tributary offices and that available between a terminal office and an intermediate repeater station of the communication network. Those channels are specified in E1 and E2 bytes respectively in the SDH transmission frame (hereinafter the channels via the E1 and E2 bytes are called E1 and E2 channels, respectively). 
     There have been practiced two ways of calling the other end by using the order-wire system: a way to use an oral sound and the other to give an audible signal such as a ringing tone which is sounded by sending a dual tone multiple frequency (abbreviated to DTMF) signal. The present invention relates to the latter way of the order-wire system. Accordingly, a call controlling device which is high in reliability of the device and high in maintainability of the communication system is in great demand. 
     2. Description of the Related Art 
     FIG. 1 shows a network system which the present invention is applied to. The network system includes terminal equipment  70  provided between wire transmission lines and terminal equipment  80  provided between wire and radio transmission lines. For easy understanding of the order-wire system, the terminal equipment are simplified and intermediate repeater stations which are provided between terminal equipment, are omitted in FIG.  1 . 
     The terminal equipment using the SDH transmission method, for example, is comprised of transceivers (XCVR)  71 / 75  and  81 / 85  corresponding to up/down lines, for transmitting and receiving a transmission signal; data controllers (DCONT)  72 / 74  and  82 / 84  corresponding to up/down lines, for extracting and inserting E1- and E2-byte signals from and in the transmission signal; and order-wire controllers (abbreviated to ORDW CONT)  73 ,  83  for controlling the order-wire system. 
     The order-wire system is equipped with first and second telephones for communicating respectively via the E1- and E2-byte signals (hereinafter may called E1 and E2 channels). It extracts the E1- and E2-byte signals from the transmission signal and decodes the signals to reproduce sound and voice on the telephones. It also encodes sound and voice generated from the telephones into E1- and E2-byte signals and inserts the signals in the transmission signal. 
     Prior to communication via voice, a calling party sends out the E1-byte signal, for example, into which the phone number of the first telephone is encoded, with the signal inserted in the transmission signal. In a called party, the E1-byte signal is extracted from the received transmission signal and encoded into a DTMF signal, for example, which in turn is decoded into a phone number. When the phone number is detected as belonging to one of the first and second telephones, a call is made on the telephone by sounding a ringing tone. 
     In a call controlling device of the related art, using the DTMF signal, for example, there were two methods of controlling a call: 
     The first method had two sets each of a telephone for receiving a call, a DTMF decoder for decoding a DTMF signal into a digital phone-number signal and a call controller for making a call on the telephone based on the phone-number signal, each set corresponding respectively to the E1 and E2 channels. Thus, the E1- and E2-byte signals were respectively input to the DTMF decoder and each set detected and controlled a call directed to the first and second telephones independently. 
     The second method had a single set of a telephone, a DTMF decoder and a call controller. The E1- and E2-byte signals were selectively input to the DTMF decoder by using a manual switch to detect and control a call to the telephone. 
     It is a problem of the related art that the call controlling device of the first method is large-sized and costly and decreases in reliability of the device because it requires large amount of circuitry including two separate sets of the circuits. It is another problem of the related art that the call controlling device of the second method decreases in maintainability of the system because it involves a manual switching operation, preventing maintenance personnel from communicating immediately as occasion demands. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a call controlling device of the order-wire system, which is small-sized, low-cost and high in reliability of the devices. It is another object of the present invention to provide a call controlling device of the order-wire system, which is high in maintainability of the communication system. 
     To achieve the above and other objects, the present invention provides a plurality of indicators, a plurality of detectors and a call controller. In a call controlling apparatus for receiving input signals including a call signal through respective communication channels and making a call, a plurality of the indicators corresponding respectively to the channels indicate the call. A plurality of the detectors corresponding respectively to the channels respectively detect the call signal in the input signals. The call controller makes the call on the indicators based on the call signals detected by the detectors. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a network system which the present invention is applied to; 
     FIG. 2 is a block diagram illustrating the principle of the call controlling device of the present invention; and 
     FIG. 3 is a detailed block diagram illustrating the call controlling device of the present invention. 
     Throughout the above-mentioned drawings, identical reference numerals are used to designate the same or similar component parts. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 is a block diagram illustrating the principle of the call controlling device of the present invention. The call controlling device is comprised of detectors (DET)  103 ,  203 , a selector (SEL)  303 , a determiner (DETNR)  300 , a call controller (CALL CONT)  305  and telephones (TEL)  107 ,  207 . 
     Input signals each including a call signal consisting of a phone-number signal preceded by a predetermined signal, are input to the call controlling device through respective communication channels. The detectors  103 ,  203  which are responsive to the input signals, each detect therein the predetermined signal and phone numbers. The determiner  300  checks the detector outputs for the predetermined signal to determine which detector has detected the phone number. 
     The selector  303  selects one of respective outputs of the detectors  103 ,  203  based on the determination by the determiner  300 . The call controller  305 , which has a phone number list (not shown) for the telephones  107 ,  207 , compares the phone number selected by the selector  303  with those of the list and on a match, conducts the call control so as to give a ringer tone to the corresponding telephone. 
     Thus, the selector  303  selectively outputs to the call controller  305 , the phone number detected by the detectors  103  based on the determination by the determiner  300 , meaning that a call is automatically received by one of the telephones without the maintenance personnel&#39;s intervention. 
     FIG. 3 is a detailed block diagram illustrating the call controlling device of the present invention. The call controlling device shown in FIG. 3 is divided mainly into circuitry for detecting a call signal based on the E1- and E2-byte signals extracted from the transmission signal, circuitry for inputting telephone signals received from the line to the telephone and circuitry for sending telephone signals generated from the telephone to the line. The method for extracting/inserting the E1- and E2 byte signals from/in the transmission signal is well known and is not explained here. 
     Signal lines  50 ,  51  input/output the telephone signals (including call and voice signals) from/to the preceding station; and signal lines  60 ,  61  input/output the signals from/to the succeeding station. The signal lines  50 ,  51  input/output the E1- and E2-byte signals from/to the preceding station. The signal lines  60 ,  61  perform the same with respect to the succeeding station. Amplifiers  52 - 59  amplify the signals which are input/output from/to the signal lines  51 ,  52 ,  61  and  62 . 
     A first sound coupler/distributor (CPLR-DISTR)  10  passes the telephone signal received from the preceding station to the succeeding station through the lines  50  and  60  or vice versa and distributes the signal to switches  11 ,  12 . It also transmits to the signal lines  50 ,  60 , a ringback tone (hereafter abbreviated to RBT) signal and a telephone signal output from an RBT sender  38  and a first 4W/2W transformer (4W/2W XFMR)  15 , respectively. A second voice coupler/distributor (CPLR-DISTR)  20  performs the same operation for the signal lines  51 ,  61 , switches  21 ,  22  and a second 4W/2W transformer (4W/2W XFMR)  25  as the first sound coupler/distributor  10 . 
     First, a case is explained in which the E1-telephone (E1-TEL)  17  is called. In this example, a predetermined signal # is added to phone numbers, at the first-digit position thereof to form a call signal. The # is used in common with the telephones throughout the system. Thus, the E1-telephone  17  is assumed to have a phone number #0001. 
     A DTMF signal representing the number #0001, which is received from the preceding station, is input to the switches  11 ,  12  through the signal line  50  and the first voice coupler/distributor  10 . 
     The switch  11  turns off (opens) and turns on (closes) when the E1-telephone  17  is in an on-hook state and in an off-hook state, respectively. To the contrary, the switch  12  turns on and turns off when the telephone is in the on-hook state and in the off-hook state, respectively. Thus, the switch  12  is on when a call is initiated and before the E1-telephone  17  is being called, at which time the telephone is in the on-hook state. 
     Accordingly, the DTMF signal representing the phone number #0001 is input to a first DTMF decoder (DTMF DCDR)  13 . The first DTMF decoder  13  decodes the DTMF signal into a combination of 4-bit numeric data representing a digit of a phone number and a 1-bit timing signal. 
     A first # detector (# DET)  14 , which is responsive to an output of the first DTMF decoder  13 , outputs a high level (hereafter abbreviated to H) only while a signal representing the # is being input thereto. When the first # detector  14  outputs H, an E1/E2 determiner (E1/E2 DETNR)  30  outputs H. When the second # detector (# DET)  24  outputs H, the E1/E2 determiner  30  outputs a low level (hereafter abbreviated to L). 
     Therefore, a call is directed to the E1-telephone  17  or the E2-telephone  27  depending on whether the E1/E2 determiner  30  outputs H or L. When the E1/E2 determiner  30  outputs H, a number selector (NO SEL)  33  selectively outputs the output of the first DTMF decoder  13  to a number checker (CHKR)  35 . 
     The number checker  35  previously holds the phone numbers of the E1-telephone  17  and E2-telephone  27 , which numbers are set therein by a personal computer via the bus  34 , for example. When the output of the E1/E2 determiner  30  is H, the number checker  35  recognizes that the output of the first DTMF decoder  13  (i.e., the signal resulting from the E1-byte signal) is coming from the number selector  33 . The number checker  35  compares the phone number of E1-telephone  17  held therein with the number output from the number selector  33 . When a result of the comparison is equal, the number checker  35  outputs H. 
     When the number checker  35  outputs H to the S input of an R-S flip-flop  36 , the flip-flop  36  outputs H to a call selector (CALL SEL)  37 . The call selector  37  has a calling method previously set therein by the personal computer. For example, a method is selected from lighting an LED or sounding a buzzer both provided in the terminal equipment or activating a remotely-located calling device by switching on/off a relay contact. A call to the telephone is controlled by a CALL signal output from the call selector  37 . 
     With the call controlling device so constructed, a call to maintenance personnel is controlled as follows. When the flip-flop  36  outputs H to the call selector  37 , the CALL signal is output (i.e., becomes H) to activate the RBT sender  39 , buzzer  40  and/or ringer  41 . The RBT sender  39  outputs a ringback tone to the calling party, indicating that the called party is being called. 
     On receiving H from the E1/E2 determiner  30 , switches  38  close contacts “c” and “a”. As a result, the RBT signal is transmitted from the RBT sender  39  to the signal lines  50 ,  60  as the E1-byte signal through the first voice coupler/distributor  10 . Also, the output of the ringer  41  is sent to the E1-telephone  17  to call the maintenance personnel by giving a ringing tone. 
     Next, the maintenance personnel&#39;s talk over the telephone is controlled as follows. When the maintenance personnel lifts the E1-telephone receiver, an off-hook signal (E1OH) is generated. The signal controls switches  11 ,  12  and  16  and is sent to the first call stopper  31 . On receiving the E1OH signal, the first call stopper  31  outputs H. The first call stopper  31  is designed so as to output H whichever signal E1OH or E2OH it may receive, to indicate the E1-telephone  17  or E2-telephone  27  is in the off-hook state. 
     On receiving H at the input R from the first call stopper  31 , the flip-flop  36  outputs L. Then, the call selector  37  turns the CALL signal L, causing the RBT sender  39 , buzzer  40  and ringer  41  to stop and therefore, to stop the call. 
     When the E1OH signal is H, the switches  11 ,  16  are turned on and the switch  12  is turned off. Therefore, the voice signal transmitted from the calling-party and received here through the E1 channel is carried to the E1-telephone  17  through the first voice coupler/distributor  10 , switch  11  and the first 4W/2W transformer  15 . Also, the voice signal generated from the E1-telephone  17  is transmitted to the E1 channel through the first 4W/2W transformer  15 , switch  16  and the first voice coupler/distributor  10 . Here, the line connecting the E1-telephone  17  to the first 4W/2W transformer  15  is a bidirectional 2-wire circuit, whereas the other lines connected to the first 4W/2W transformer  15  are unidirectional 4-wire circuits. The first 4W/2W transformer  15  converts a 4-wire-circuit signal to a 2-wire-circuit signal or vice versa. 
     When the maintenance personnel ends the talk and replaces the E1-telephone receiver, the E1OH signal becomes L, causing the switches  11 ,  12  and  16  to restore to the original state and the first call stopper  31  to output L. A call to the E2-telephone  27  is controlled in the same way as to the E1-telephone  17  except the following: On receiving H from the second # detector, the E1/E2 determiner outputs L and as a result, the switches  38  connect the contacts “c” to “b”. Then, the number selector  33  selectively outputs the output of the second DTMF decoder  23  to the number checker  35 . 
     Further, a case is explained in which while a call having a first phone number (with a first #) is being made to a telephone from a channel (e.g., E1 channel), another call having a second phone number (with a second #) is made to the other telephone from the other channel (e.g., E2 channel). 
     First, a case is taken in which the E1/E2 determiner  30  is outputting H after the first # detector  14  detects the first #, whereas the call selector  37  has not yet output the CALL signal. When the second # detector  24  detects the second # in this state, the E1/E2 determiner  30  outputs L to resume a call to the E2 telephone  27  in the same sequence as in the aforesaid call to the E1 telephone  17 . 
     Second, a case is taken in which the E1 telephone  17  is being called after the first # detector  14  detected the first #, i.e., the switches  38  have the contact “c” connected to “a” and the call selector  37  is outputting the CALL signal with the E1/E2 determiner  30  outputting H. When the second # detector  24  detects the second # in this state, a second call stopper (CALL STPR)  32  functions as follows: 
     Except for the second call stopper  32 , when the second # detector  24  detects the second #, the E1/E2 determiner  30  may output L and as a result, the switches  38  may connect the contact “c” to “b”, eventually sounding a ringing tone on the E2 telephone  27  without even the second phone number being checked. To prevent this inconvenience, the second call stopper  32  is so designed as to output H when the second # detector  24  detects the second # while the CALL signal is H. That is, the CALL signal is turned off by resetting the flip-flop  36  when the second # is detected while a preceding call is in progress, to be prepared to detect a phone number coming from the E2 channel. Thereafter, the call to the E2 telephone  27  is controlled as in the aforesaid procedure to call the E2 telephone  27 . 
     Hereinafter, a case is explained in which a telephone of this call controlling device makes a call on a telephone of another one. Lifting the E1-telephone receiver turns the E1OH signal H, causing the switches  11 ,  16  to turn on and the switch  12  to turn off. Accordingly, the E1 telephone  17  can transmit the phone number in the DTMF signal and receive a voice signal from an external telephone. A call made from the E2 telephone  27  is controlled in the same way. 
     As described above, in FIG.  2  and the associated description, for example, the present invention provides in the call controlling device, two detectors each for the E1 and E2 channels and only one call controller in common with the detectors. Thus, by having the detectors share the call controller and therefore, minimizing the amount of circuitry, the present invention provides a highly reliable call controlling device. Also, by having the call controller select one of the detectors that has detected the predetermined signal and therefore, automatically selecting one of the E1- and E2-telephones to which a call is directed, it provides a call controlling device which is high in maintainability of a communication system. 
     Although the # is used for an example, the particular signal is not limited to #, but may be any if it is the same throughout a system, or even different only if it is the same for each corresponding channel. Two channels (E1 and E2 channels) were taken for an example; however, the present invention can easily be applied to three or more channels. Moreover, the DTMF signal is used as an example; however, the call signal is not limited to the DTMF signal but may be of any type only if it can identify a telephone. 
     As is apparent from the above description, since the present invention allows plural communication channels automatically share only one call controller and thereby to make a call to a corresponding telephone, it can provide a small-sized, low-cost and high in reliability of the device and high in maintainability of a communication system.