Abstract:
There is disclosed a telephone exchange emulator for POTS and ISDN telephone lines comprising, a main unit including at least one of at least one Plain Old Telephone Service (POTS) line card or at least one Integrated Services Digital Network (ISDN) line card, and at least one V5.1 interface card, each of one of the at least one POTS or the at least one ISDN line card, and the at least one V5.1 interface card in communication with ports. These ports are adapted for receiving signals from communication devices, including for example, POTS and ISDN telephones. There is also a switch simulator in communication with the at least one V5.1 interface card. There is also a controller, typically a workstation with network management software for managing (controlling) the main unit and switch simulator. A method for emulating a telephone exchange is also disclosed.

Description:
TECHNICAL FIELD  
         [0001]    The present invention is directed to the field of testing of telecommunication equipment, and in particular, to systems and methods that emulate exchanges that support multiple services, such as Integrated Services Digital Network (ISDN) and Plain Old Telephone Service (POTS).  
         BACKGROUND  
         [0002]    Access systems are used in telecommunications networks to transport telephony or other services across a network. In a conventional telephone network, access systems function to transport voice and data between the local exchange and the subscribers&#39; equipment, typically located at a business or residential site. For example, commercially available access systems include BroadAccess™ or LightAccess™, both available from ADC Teledata, Herzlia, Israel, both of which support POTS and ISDN services.  
           [0003]    Access systems, such as those detailed above, and in particular, those supporting ISDN lines, are typically tested, to determine load on the system and load on the ISDN interfaces. Testing this kind of a system requires ISDN lines for Bit Rate Error (BER) testing, call process testing, traffic testing and various other tests. The use of commercial ISDN lines for this testing procedure is not practical, as large numbers of “lines” must be ordered from a telephone company. Heavy usage of these lines may be costly and the required amount of lines may not be available from the local telephone service provider.  
           [0004]    Alternatively, commercial exchange simulators for both POTS and ISDN are available. However, these systems are expensive and have a limited number of lines that for most testing procedures simply are not enough. For example, an Ameritec AM7 (Ameritec Corporation, Covina Calif.) POTS exchange simulator has only twenty POTS lines. Similarly, ISDN exchange simulators, such as those available as the EMUTEL® series of ISDN exchange simulators, from Arca Technologies, 5 Third Street, San Francisco, Calif. 94103, are also limited to eight lines at a high cost. Moreover, both of the above described systems lack flexibility for both ISDN and POTS lines as they support only one line type, ISDN or POTS. As a result, these systems do not support calls between ISDN and POTS lines.  
           [0005]    Finally, even if separate simulators for ISDN and POTS lines are employed, testing capability is and remains limited. This is because conventional simulators typically do not communicate with one another, and thus, POTS to ISDN calls as well as ISDN to POTS calls can not be readily simulated.  
         SUMMARY  
         [0006]    Embodiments of the present invention improve on conventional exchange simulators by allowing a single simulator to present various combinations of services on its communications lines. For example, one embodiment allows for the simulation of ISDN Basic Rate Interface (BRI), POTS and switch interface ports (such as V5.1 and V5.2) in the same system. In this embodiment, testing capacity is increased, when compared to conventional simulators, as the system supports ISDN to POTS as well as POTS to ISDN calls.  
           [0007]    One embodiment of the present invention is directed to emulated exchanges comprising a main unit including at least one access device configured for supporting at least one line type, typically two line types, such as POTS and ISDN, and at least one switch interface card, for example a V5.1 interface card, and a plurality of ports in communication with the main unit. These ports are adapted for receiving signals from communication devices. There is also a switch simulator in communication with the at least one switch interface card.  
           [0008]    In one embodiment, the switch simulator is configured for emulating a digital exchange, includes V5.1 and/or V5.2 ports, and is designed for processing POTS and/or ISDN data. The main unit typically supports the line types in the form of line cards, typically POTS and ISDN line cards in various combinations. These line cards are in communication with their respective ports. There is also a controller, typically a wokstation with network management software for managing (controlling) the main unit and switch simulator.  
           [0009]    Another embodiment is directed to a method for emulating a telephone system exchange. This method includes providing a switch simulator configured for emulating a digital exchange and for opening at least one voice path between connected telephone devices. The method also includes monitoring at least one telephone line corresponding to at least one calling telephone for line conditions, responding to a change in line conditions, signaling the switch simulator to receive dialed digits, activating the switch simulator for placing a call to the telephone line corresponding to the received dialed digits, and initiating a signal for generating a ringing signal to the telephone line of an intended recipient. The intended recipient telephone line corresponds to that of the dialed digits. This method is such that calls can be completed between two POTS telephones, between two ISDN telephones, and between POTS and ISDN telephones. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Attention is now directed to the attached drawings, wherein like reference numerals or characters indicate corresponding or like components. In the drawings:  
         [0011]    [0011]FIG. 1 is a schematic diagram of an embodiment of the invention,  
         [0012]    [0012]FIG. 2 is a schematic diagram of an exemplary testing set-up employing an embodiment of the invention,  
         [0013]    [0013]FIG. 3 is a schematic diagram of a second exemplary testing set-up employing an embodiment of the invention, and  
         [0014]    [0014]FIG. 4 is a schematic diagram of a third exemplary testing set-up employing an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]    [0015]FIG. 1 details a schematic diagram of one embodiment of a system  20  that is adapted to function as an exchange emulator. This system  20  includes a main unit  22  coupled to a switch simulator  24 . The main unit  22  and switch simulator  24  are connected to a computer  26 . Computer  26  configures and manages the operation of the main unit  22  and switch simulator  24 . The system  20  terminates in an interface  30  that accommodates POTS ports  32 , ISDN ports  34 , typically defining a “U” interface, V5.1 ports  36  and V5.2 ports  38 . It is understood that the port types identified here are provided by way of example and not by way of limitation. In other embodiments, ports for other acceptable line types and switch interfaces are provided.  
         [0016]    The main unit  22  is an access device, that is configured to be a single unit primary access multiplexer. Its configuration is such that it typically supports single or multiple POTS and single or multiple ISDN line cards in the same subrack  42 , allowing for a mixed configuration of all ports at the interface  30 . Main unit  22  is also configurable to include single or multiple V5.1, or other protocol, interface cards  44 . POTS lines  45  and ISDN lines  46  extend from the main unit  22  to the respective ports  32 ,  34  of the interface  30 . In one embodiment, the main unit  22  is a LightAccess™ (TIMUX™), available from ADC Teledata, Herzlia, Israel, the LightAccess™ module functions as a single unit primary access multiplexer modified so as to include V5.1 interface cards  44  and some selected combination of ISDN and POTS cards in subrack  42 . This configuration supports up to 150 POTS lines, up to 60 ISDN lines, or a combination of both types of lines.  
         [0017]    The switch simulator  24 , serves to simulate a digital exchange with, for example, V5.1 and V5.2 ports. Each of the ports at the interface of the switch simulator  52  is adapted to be configured to be either a V5.1 or a V5.2 port or port that supports another appropriate switch protocol. Some of these V5.1 ports connect via line  50  (only one line shown for example) to the V5.1 interface cards  44 . Other V5.1 ports connect via line(s)  51  to the V5.1 port(s)  36  at the interface  30 . The V5.2 ports connect via another line(s)  54  to the V5.2 ports  38  at the interface  30 . In one embodiment, this switch simulator  24  is a V5SWIM™ switch simulator, available from TdSoft, Herzlia, Israel (TdSoft is a Subsidiary of ADC Teledata, Herzlia, Israel), and is adapted to process data from both POTS and ISDN lines once passed therethrough.  
         [0018]    The computer  26  is typically a workstation with network management software, for managing the system, and V5SWIM™ configuration software for configuring the system. The V5SWIM™ configuration is provided by the manufacturer of the V5SWIM™ Switch Simulator (TdSoft). The computer  26  connects to the main unit  22  and switch simulator  24 , typically by wired links  56 ,  57 . In one embodiment, communication between the computer  26  and switch simulator  24  is by a protocol such as TCP/IP, and communication between the computer  26  and the main unit  22  is by a RS232 protocol.  
         [0019]    [0019]FIG. 2 details an exemplary operation of the system  20  in a test set-up. Here, a POTS telephone  60  is connected to one of the POTS ports  32   a  by line  64 , and it initiates an outgoing call to another POTS telephone  61 , connected to another one of the POTS ports  32   b , by line  65 . When the handset is picked up, the main unit  22  identifies an “off-hook” condition and converts it to an “off-hook” message to the switch simulator  24 . The switch simulator  24  responds by activating the relevant line and generating a dial-tone to the line. The main unit  22  transfers the dial-tone to the telephone  60 . The user then dials a number on the telephone  60 , either by pulse or by Dual-Tone-Multi-Frequency (DTMF) dialing. If pulse dialing is used, the main unit  22  converts the dialed digits to messages, which are transferred to the switch simulator  24  via line  50  to the specific V5.1 interface  52 . If DTMF dialing is used, the digits are transferred to the switch simulator  24  on the voice-path via line  50  to the V5.1 interface  52 .  
         [0020]    In either case, the switch simulator  24  analyzes the dialed digits, and initiates a call to the specific line. Here, the specific line is the line connected to the telephone  61 . The switch simulator  24  initiates a ringing message to the main unit  22 , which generates a ringing signal to the telephone  61 . When the telephone  61  is answered (picked up), the main unit  22  generates an off-hook message to the switch simulator  24 . The switch simulator  24  generates an “end of ring” message, that causes the main unit  22  to stop ringing the telephone  61 . The switch simulator  24  also opens the voice-path between the two telephones  60 ,  61 , and thus, the call, has been established.  
         [0021]    In a similar way, system  20  is adapted to allow a POTS Telephone  60 ,  61 , for example, to initiate a call to an ISDN telephone  70 ,  71 , for example, connected by lines  74 ,  75 , to one of the ISDN ports  34   a ,  34   b  via lines  74 ,  75  through the respective Network Termination Unit (NT1)  80 ,  81 . Also, system  20  is adapted to allow the ISDN telephone  70  to initiate a call to a POTS telephone  60 , or to another ISDN telephone  71 , connected through the other NT1  81 .  
         [0022]    [0022]FIG. 3 details a second exemplary operation of the system  20  in a test set-up, which is used for testing an access system  90 , for example a BroadAccess™ access system. The BroadAccess™ is formed from two units, a Central Unit (CU)  91 , and a Remote Unit (RU)  92 , connected by a link  93 . The link  93  is a wired, typically fiber or copper, wireless or other appropriate link. The CU  91  interfaces with the exchange emulator  20  with any of a number of different interfaces. For example, in one embodiment, the CU  91  provides any appropriate combination of POTS interfaces  94 ,  95 , ISDN (U) interfaces  96 ,  97 , V5.1 interfaces  98  and V5.2 interfaces  99 . In this exemplary operation, each one of the interfaces is connected to the respective matching ports  32   a ,  32   b ,  34   a ,  34   b ,  36  and  38  in the system  20 .  
         [0023]    Specifically, from the CU  91 , lines  100 ,  101  connect the POTS interfaces  94 ,  95  to the respective POTS ports  32   a ,  32   b  of the system  20 . The ISDN interfaces  96 ,  97  are connected by lines  102 ,  103  to the respective ISDN ports  34   a ,  34   b  of system  20 . The V5.1 interface  98  connects to the V5.1 port(s)  36  of the system  20  connected by lines  106 , and the V5.2 interface  99  connects to the V5.2 port(s)  38  of the system  20  by lines  107 .  
         [0024]    The Remote Unit (RU  92 ) has POTS interfaces  110 ,  111 , for connecting to the respective POTS telephones  112 ,  113  via the respective lines  114 ,  115 , and ISDN interfaces  120 ,  121 , for connecting to the respective ISDN telephones  122 ,  123 , through ISDN NTs  124 ,  125 , typically NT1 units, over lines  126 ,  127 , respectively.  
         [0025]    In this exemplary operation, a POTS telephone  112  is connected to one of the POTS interface  110  of the RU  92  by a line(s)  114 , and it initiates an outgoing call to another POTS telephone  113 , connected to another one of the POTS interfaces  111  by line(s)  115 . When the handset of telephone  112  is picked up, the RU  92  identifies an “off-hook” condition at its interface  110 , and transfers it to the CU  91  through the link  93 . In this example, the CU  91  reproduces the “off-hook” signal at its corresponding POTS interface  94 . The “off-hook” signal is transferred by line  100  to the POTS port  32   a  of system  20 . The main unit  22  identifies an “off-hook” condition, and converts it to an “off-hook” message to the switch simulator  24 .  
         [0026]    The switch simulator  24  responds by activating the relevant line and generating a dial-tone to the line. The main unit  22  transfers the dial-tone to the relevant POTS port  32   a , and is transferred back through line  100  to the POTS interface  94  of the CU  91 . The CU  91  transfers the dial tone through the link  93  to the corresponding POTS interface  110  of the RU  92 , which transfers it by line  114  to the telephone  112 .  
         [0027]    Upon hearing a dial tone, the user then dials a number on the telephone  112 , either by pulse or by Dual-Tone-Multi-Frequency (DTMF) dialing. If pulse dialing is used, the pulses are transferred from the RU  92  through link  93  to the CU  91 , and then to the system  20 . The main unit  22  converts the dialed digits to messages, which are transferred to the switch simulator  24  via line  50  to the specific V5.1 interface  52 . If DTMF dialing is used, the digits are transmitted from the RU  92  through link  93  to the CU  91 , and then transferred to the switch simulator  24  on the voice-path via line  50  to the V5.1 interface  52 .  
         [0028]    In either case, the switch simulator  24  analyzes the dialed digits, and initiates a call to the specific line. Here, the specific line is the line connected to the telephone  113  through the access system  90 . The switch simulator  24  initiates a ringing message to the main unit  22 , which generates a ringing signal at the POTS interface  33 , corresponding to the called line, of the system  20 . The POTS port  32   b  is connected to the POTS interface  95  of the CU  91 , by line  101 . The ring detector at the POTS interface  95  of the CU  91 , detects the ringing signal, and transfers it through link  93  to the RU  92 , which reproduces the ringing signal at its corresponding POTS interface  111 . This causes the telephone  113  to ring.  
         [0029]    When the telephone  113  is answered (picked up), this is identified as an “off-hook” condition at the POTS interface  111  of the RU  92 , which transfers it through link  93  to the CU  91 . The CU  91  reproduces the “off-hook” condition at its corresponding POTS interface  95 , which is transferred by line  101  to the POTS port  32   b  of the system  20 . The main unit  22  generates an off-hook message to the switch simulator  24 . The switch simulator  24  generates an “end of ring” message, that causes the main unit  22  to stop ringing at POTS port  32   b . This stops the CU  91  from identifying a ringing signal at its POTS interface  95 , and it therefore stops transferring a ring message to the RU  92  through the link  93 . This causes the telephone  113  to stop ringing. The switch simulator  24  also opens the voice-path between the two POTS ports  32   a ,  32   b , which are connected through the access system  90  to telephones  112 ,  113 , and thus, the call has been established.  
         [0030]    In a similar way, system  20  is adapted to allow a POTS Telephone  112 ,  113 , for example, to initiate a call to an ISDN telephone  122 ,  123 , through the respective Network Termination Unit (NT1)  124 ,  125 . Also, system  20  is further adapted to allow the ISDN telephone  122  to initiate a call to a POTS telephone  112 , or to another ISDN telephone  123 , connected through the other NT1  125 .  
         [0031]    [0031]FIG. 4 is a schematic diagram of a third exemplary testing set-up employing an embodiment of the invention. In this embodiment, exchange emulator  420  and bulk call generator  500  combine to test the operation of unit under test  490 . Unit under test  490 , comprises, for example, an access system such as a digital loop carrier (DLC) or other appropriate communication circuit.  
         [0032]    Exchange emulator  420  provides an interface at ports  430  for unit under test  490 . Ports  430  comprise ports that support one or more of V5.1, V5.2, or other appropriate switch interfaces, POTS, ISDN, or other line or service type. Ports  430  are coupled to main unit  420  and switch simulator  424 . Main unit  422  comprises, in one embodiment, an access device that is configured to be a single unit primary access multiplexer. In one embodiment, main unit  422  is a LightAccess (TIMUX), available from ADC Teledata, Herzlia, Israel. In one embodiment, the LightAccess module functions as a single unit primary access multiplexer modified so as to include V5.1 interface cards and some selected combination of ISDN and POTS cards in a single subtrack. This configuration supports up to 150 POTS lines, up to 60 ISDN lines, or a combination of both types of lines. In other embodiments, the main unit  20  includes line and interface cards for other appropriate line types and switch interfaces.  
         [0033]    Switch simulator  424 , serves to simulate a digital exchange with at least one of V5.1 and V5.2 ports coupled to ports  430 . In one embodiment, this switch simulator  424  is a V5SWIM switch simulator, available from TdSoft, Herzlia, Israel (TdSoft is a Subsidiary of ADC Teledata, Herzlia, Israel), and can process data from both POTS and ISDN lines once passed therethrough.  
         [0034]    The computer  426  is typically a workstation with network management software, for managing the exchange emulator  420 , and V5SWIM configuration software for configuring switch simulator  424 . The V5SWIM configuration is provided by the manufacturer of the V5SWIM Switch Simulator (TdSoft). In one embodiment, communication between the computer  426  and switch simulator  424  is by a protocol such as TCP/IP, and communication between the computer  426  and the main unit  422  is by a RS232 protocol.  
         [0035]    In one embodiment, unit under test  490  is monitored during operation to determine load on the system, load on ISDN interfaces, Bit Rate Error (BER) performance, call processing performance, traffic handling and various other characteristics of the unit under test. In one embodiment, this analysis is performed based on data monitored by computer  426  and bulk call generator  500 .  
         [0036]    Bulk call generator  500  generates calls to be processed by unit under test  490 . Bulk call generator  500  generates calls of at least two service types. For example, bulk call generator  500 , in one embodiment, generates POTS and ISDN calls. In one embodiment, bulk call generator  500  is constructed as described in commonly assigned, co-pending application Ser. No. 09/593,903, filed on Jun. 14, 2000 and entitled BULK CALL GENERATOR (the 903 Application). The 903 Application is incorporated herein by reference. In this embodiment, calls of a first line type processed by unit under test  490  are selectively connected by exchange emulator  420  to lines of either the first or second line type.  
         [0037]    In operation, bulk call generator  500  generates calls that are designed to test the operation of unit under test  490 . For example, bulk call generator  500  generates a number of calls n lines of one or more line types, e.g., lines that support ISDN and POTS services. These calls are processed by unit under test  490  and passed to exchange emulator  420  at ports  430 . Main unit  422  provides signals to switch simulator  424  to make the connection. Switch simulator  424  generates signals that connect through port  430  to a line of one of the supported line types. Computer  426  and bulk call generator  500  monitor the operation to allow analysis of the operation of unit under test  490 .  
         [0038]    While embodiments of the present invention have been described, so as to enable one of skill in the art to practice the present invention, the preceding description is intended to be exemplary only. It should not be used to limit the scope of the invention, which should be determined by reference to the following claims.