TRANSMISSION TEST LINE AND TEST-LINE TERMINATIONS DIRECTORY

1.   GENERAL

1.01      The purpose of this practice if to provide a list of working NNX Codes, The Common Language Location Identification (CLLI) Codes for the associated Central Office Building, the principal geographical location served, and related test-line terminations.

1.02      Since the test numbers have been standardized, this practice will also indicate the type of test line provided for each NNX Code.

1.03      Test line or test termination are terms sometimes used interchangeably to name a testing equipment, facility, circuit, or test communication channel.  These include simple static terminations and relatively complex testing circuits capable of applying marginal tests and recognizing and replying to specific signals received.

1.04      Test lines for intertoll trunks are known as National Code Test Lines (or test terminations) and are a part of the basic maintenance pattern in the intertoll dialing plan.  These National Code Test Lines provide assistance in connection with maintenance tests at Testboards and automatic testing equipment.  These test lines and details of operation are shown in Section 2 of this practice.

1.05      Bell System Practice 660-450--301 contains information on testing at Testboards and locations other than Testboards.

1.06      Local Test Lines (or terminations) are located in the end offices (local central offices) and complement the manual and automatic test facilities at the outgoing end of the trunk under test. These test lines and details of operation are shown in Section 3 of this practice.

1.07      This practice is organized in sections to simplify the proceures for additions and corrections:

     Section No. 1 - General Information
     Section No. 2 - National Code Test Lines
     Section No. 3 - Local Office Test Lines
     Appendix 1    - Numerical list of NNX Codes and Associated Test
                     Numbers


2.   NATIONAL CODE TEST LINES

2.01      National Code Test Lines (or test terminations) are part of the basic maintenance pattern in the distance dialing plan for the maintenance of intertoll trunks.  These test lines provide assistance in connection with maintnence tests at testboards and automatic testing equipment.

2.02      National Code Test Lines 100, 101, 102, 103, and 104 will return a steady "Off-Hook" signal which removes the single frequency signaling tone that would otherwise interfere with certain measurements.

2.03      It is important that the equipment associated with the test line codes be well maintained.  Regular checks should be made of their performance as covered in the Bell System Practice.

2.04      National Code Test Lines include fixed terminations and relatively complex testing circuits.  Some are capable of recognizing, testing, and replying to specific signals.  The more complicated test lines can be used to make two-way net loss measurements and noise test without assistance from the far-end office.

2.05      Each test line circuit is connected automatically by the far-end switching equipment upon receipt of the proper code number. It is disconnected either on a time interval basis or when released at the originating end.

2.06      Reference:
               Code 100 - Bell System Practice 660-440-100
               Code 101 - Bell System Practice 660-440-101
               Code 102 - Bell System Practice 660-440-102
               Code 103 - Bell System Practice 660-440-103
               Code 970 - Bell System Practice 660-440-113

2.07      Code 100 - Noise and Balance Terminations
          Provides a connection to a test line termination at the terminals of intertoll trunks for noise and balance testing.  The features of this test line termination are:
          a)   Returns "Off-Hook" supervision to the calling end as
               long as the trunk is held by the calling end.
          b)   Provides a "Pad Control" feature at offices having
               pad control arrangements.  Tests are normally made
               in the "Pad Out" condition.
          c)   Provides a 600 or 900 Ohm impedance termination.  This
               impedance simulates the impedance at 1000 hertz
               presented by the intertoll trunk at the point at
               which the termination is connected.
                 NOTE:   There is a program underway to convert all
                         Code 100 test lines to Combination Milliwatt
                         and Balance test lines.  The new test line
                         enables both far-near loss and noise
                         measurements to be made on one connection.
                         The features of the new termination are:
                         off-hook followed by 5.5 seconds of 1000
                         hertz, then 5.5 seconds of 600 or 900 Ohm
                         impedance termination followed by one second
                         of on-hook, then 600 or 900 Ohm termination
                         until the calling end disconnects.

2.08      Code 101 - Toll Testboard Communication and Test Trunk
          Provides a dial communication line into the testboard that maintains the intertoll trunks.  The features of this test line are:
          a)   Returns "Off-Hook" supervision to the originating point
               when the trunk is answered at the testboard position
               and "On-Hook" supervision when the testboard
               disconnects.
          b)   A recall signal from the originating point is indicated
               on the testboard position cord lamp.  A recall signal
               may be returned to the originating point by operating
               the proper testboard position key.
          c)   Provides a "Pad-In" condition during connection at
               offices having pad control arrangement.  A  pad control
               key is provided at testboards to check operation of
               switching pads.

2.09      Code 102 - One Milliwatt, 1000-hertz Testing Power
          Provides access to 1000-hertz test power in various switching systems for one-way transmission measurements of intertoll trunks.  The features of this test line are:
          a)   Sends test power for approximately 10 seconds.  The
               power is then removed to assure that the test line
               will be disconnected from the intertoll trunks
               single frequency signaling.
          b)   Returns "Off-Hook" supervision when testing power
               is connected and "On-Hook" signal when it is
               disconnected.
          c)   Provides idle circuit termination in the on-hook
               condition.

2.10      Code 103 - Supervisory and Signaling Test Termination
          Provides a connection to a test circuit for overall test of supervisory and signaling path features of intertoll trunks.  The features of this test line are:
          a)   Returns "Off-Hook" supervision to the originating
               point on seizure of test trunk.
          b)   Returns "On-Hook" supervision on receipt of a ring
               forward signal.
          c)   Provides a flashing "On-Off-Hook" signal of 120 IPM
               (recorder flashes) on reciept of a second ring forward
               signal.

2.11      Code 104 - Far-End Transmission Measuring and Noise Checking
                     Circuit
          Provides a test termination for two-way transmission testing and one-way noise checking on calls originated by a Distant Automatic Transmission Test and Control Circuit (ATTC) or by a distant testboard.  The features of this test line are:
          a)   Provides for normal pad arrangement under measuring
               condition.
          b)   Receives and measures 1000 hertz, one milliwatt minus
               the circuit loss.
          c)   Arranges a network to simulate the loss indicated
               above.
          d)   Sends 100-hertz, one milliwatt tone toward testing pad.

2.12      Code 105 - Automatic Transmission Measuring System (ATMS)
                     Circuit
          Provides access to an ATMS responder used for automatic transmission measuring programs, such as ATMS and CAROT (Centralized Automatic Reporting on Trunks).  For more information on 105 test lines, see Bell System Practice 103-250-101.

2.13      Code 970 - Used for Office Balance
          Provides a connection through the crossbar switches to a spare office link terminal and the associated appearance at the manual outgoing trunk test frame.

3.   LOCAL OFFICE TEST LINES

3.01      Local office test lines (or test terminations) are provided for the maintenance of interoffice and toll switching trunks with the test originated either on a manual or automatic basis.

3.02      These test lines are reached by dialing or keying a customer-type telephone number.

3.03      Combination One Milliwatt (102-Type Test Line) and Loop
          Around
          Two terminations are provided for transmission testing of trunks.  Test calls directed to the first termination are connected to a one-milliwatt, 1000-hertz source for far-to-near end termination loss measurment.

          Two-way transmission loss measurements may be made by one person utilizing both terminations.  After having measured the far-
to-near end loss of all trunks in the group using this reference trunk, a test call is originated to the first termination.  Taking each of the remaining trunks in turn, originate a call to the second termination and connecting test power to this trunk at the near end, then measure power received at the near end on the reference trunk. By knowing the far-to-near loss of the reference trunk and the overall measurement of the two trunks, the near-to-far loss is calculated by subtraction.  The requirements for these terminations are as follows:
          a)   Trips machine ringing.
          b)   Connects one-milliwatt, 1000-hertz testing power to the
               first termination at 10-second intervals as long as the
               connection is held at the calling end and no connection
               made to the second termination.  This interval consists
               of 9 seconds test power with off-hook supervision and 1
               second no power with on-hook supervision and idle
               circuit termination.
          c)   With a connection to the first termination with the
               second termination selected, test power is removed from
               the the first termination and the transmission path of
               both terminations are directly connected, forming a
               loop.  Off-hook supervision (9 seconds), followed by
               on-hook supervision (1 second), is returned on both
               terminations.  Release of the second termination
               returns test power to the first termination.
          d)   When the second termination is selected without a
               connection to the first termination, ringing will
               be tripped and an idle circuit termination connected
               to the transmission path with on-hook supervision.
               (No.1 and No. 5 Crossbar only.  Panel and step-by-
               step ringing will not trip.)
                    Caution:  In general, a call to the second
                              termination should not be made without
                              first establishing a call to the first
                              termination, otherwise you may interfere
                              with other testing.

3.04      Nonsynchronous-Type Test Line
          The nonsynchronous-type test line provides an operation test which is not as complete as the synchronous test but can be made rapidly.  the test may be originated on either a manual or automatic basis.

          a)   For those offices where marginal-type tests cannot be
               applied directly to the incoming trunk circuit, as is
               frequently the case in connection with step-by-step
               systems, the synchronous test line (See 3.05) is not
               required and only the nonsynchronous test line is
               required.  In this case, the minimum requirements for
               this termination are as follows:
                    1)   Starts to function under control of ringing
                         signal.
                    2)   returns audible ringing for a minimum of 5
                         seconds.
                    3)   Trips machine ringing.
                    4)   Returns 60-IPM busy signal which consists of
                         low tone applied during alternate .5 second
                         intervals until disconnection.  Alternate .5
                         second off-hook and on-hook suppervisory
                         signals may or may not be returned in
                         addition to low tone.
          b)   For those offices where marginal-type test can be
               applied directly to the incoming trunk cicuit, as in
               the case of Bell System Panel and Crossbar-type
               Offices, both the synchronous (See 3.05) and the
               nonsynchronous-type test lines are required.  In
               this case, the minimum requirements for this termina-
               tion are as follows:
                    1)   Returns 60=IPM busy signal which consists of
                         low tone applied during alternate .5 second
                         intervals until disconnection. Alternate .5
                         second off-hook and on-hook supervisory
                         signals may or may not be returned in
                         addition to low tone.

3.05      Synchronous-Type Test Line
          The synchronous-type test lines provide marginal test of the supervisory and tripping functions.  Tests may be originated on either a manual or automatic basis.

          This type of test line is required for offices, such as Bell System Panel and Crossbar-type Offices where ringing, tripping and supervisory features are in the incoming trunk relay equipment and may be tested directly.  The requirements for this termination are as follows:
          a)   Test for application of the ringing signal.
          b)   Test for pretripping of machine ringing during the
               silent interval.
          c)   Provide interrupted audible ringing tone during one
               two-second interval.
          d)   Test for tripping machine ringing during three-second
               silent interval.
          e)   Provide the following supervisory tests:
               1)   An off-hook signal of approximately 1.3 seconds
                    duration for synchronizing with automatic
                    progression test equipment in the originating
                    office.  During this period, soak current is
                    applied to the supervisory relays.
               2)   The synchronizing signal is followed by two
                    seperate off-hook signals of .3 second duration
                    during which time soak current is applied to the
                    supervisory relays.
               3)   Next, an on-hook signal of approximately .2 second
                    duration is returned during which time the release
                    current is applied to the supervisory relays.
               4)   A second series of off-hook signals consisting of
                    a synchronizing signal and two flashes are
                    returned.  During each off-hook interval of this
                    series, operate current is applied to the super-
                    visory relays.  During each on-hook interval, an
                    open circuit condition is presented to the
                    supervisory relays.
          f)   Send tone signals to the originating office as follows:
               1)   Continued regular audible machine ringing tone
                    indicates a failure to trip ringing.
               2)   Audible ringing tone for .3 second intervals
                    interrupted for .2 second indicates that the
                    trunk circuit tripping feature operated on the
                    pretripping test.
               3)   A "tick-tock" tone at the rate of 120 IPM without
                    flash indicates that all tests have been completed
                    and are awaiting disconnect.

3.06      Office Identification
          An office identificaton test termination is provided so that manually originated test calls, directed to this termination from other offices within the system, will receive an indication that the proper termination was reached.  To insure that the proper office is reached, a different telephone number (four digits excluding office prefix) is required for each series of telephone numbers comprising a terminating local office unit in a Numbering Plan Area.
          a)   Electro-mechanical Offices
               The requirements for electro-mechanical office termina-
               tions are as follows:
               1)   Trip machine ringing.
               2)   Return high tone to the calling end as identifica-
                    tion tone.
               3)   Return on-hook supervision to the calling end to
                    prevent charge in case a subscriber inadvertently
                    dials this termination.
                    Note:  The present Panel and Crossbar-Type Offices
                           use a call-through test line circuit for
                           this termination which returns interrupted
                           high tone for approximately seven seconds
                           before it returns off-hook supervision.
          b)   Electronic Switching Offices
               The requirements for No. 1 and No. 2 ESS Office Termi-
               nations are as follows:
               1)   Busy tone for seven seconds with on-hook super-
                    vision.
               2)   Busy tone for seven seconds with off-hook super-
                    vision.
               3)   Following the period of busy tone, the connection
                    to the busy tone is abandoned and the ICT is
                    connected to a steady high tone trunk. A continous
                    alternating sequence of on-hook (500 - 600 ms) and
                    off-hook (1500 - 1700 ms) signals is sent until
                    disconnect.

3.07      Noise and Balance Termination-900 Ohms (100-Type Test Line)
          A termination for noise and balance (return loss and sing- ing) test is provided for all trunks.  The requirements for this termination are as follows:
          a)   Trips machine ringing.
          b)   Provides a 900-Ohm termination across the transmission
               path simulating the nominal impedance of a subscriber's
               loop.
          c)   Provides supervision at 10 second intervals as long as
               connection is held by calling end.  This consists of 9
               seconds off-hook followed by 1 second on-hook.  (Panel
               and step-by-step only.  No. 1 and No. 5 Crossbar steady
               off-hook.)  (Note - See paragraph 3.13).

3.08      Noise and Balance termination - Short Circuit
          A short circuit termination for noise and balance (return loss and singing) test reached by calling a subscriber's telephone number is required for trunks with E-type repeaters.  The require- ments for this termination are as follows:
          a)   Trips machine ringing.
          b)   Provides essentially an AC short circuit across the
               termination.
          c)   Provides supervision at 10 second intervals, as long
               as connection is held by calling end.  This consists
               of 9 seconds off-hook followed by 1 second on-hook.
               (Panel and step-by-step only.  No. 1 and No. 5 Cross-
               bar steady off-hook.

3.09      Noise and Balance Termination - Open Circuit
          An open circuit termination for noise and balance (return loss and singing) test on trunks with E-type repeaters.  The requirements for this termination are as follows:
          a)   Trips machine ringing.
          b)   Provides an impedance termination which at 1000
               hertz simulates an open termination.
          c)   Provides supervision at 10-second intervals, as long
               as connection is held by calling end.  This consists
               of 9 seconds off-hook followed by 1 second on-hook.
               (Panel and step-by-step only.  No. 1 and No. 5 Cross-
               bar steady off-hook.

3.10      Office Balance Termination - OB
          Code used for reaching outgoing trunk test frame in crossbar tandem swtiching office and operates as follows:
          a)   This code provides a connection through the crossbar
               tandem swtiched to a spare office link terminal and the
               associated jack apperance at the manual outgoing test
               frame.
          b)   Reference:  Bell System Practice 660-440-113

3.11      Far-End Transmission Measuring and Noise Checking Circuit -
          104-Type Test Line
          Provides a test termination for two-way transmission testing and one-way noise checking on calls originating by a distant automatic transmission test and control circuit (ATTC) or by an automatic transmission measuring system (ATMS), together with an appropriate test frame.

          Manual test may be made to this circuit from the following locations:
          a)   Toll Testboard
          b)   Manual outgoing trunk test frame.
          c)   Master test frame (MTF).
          d)   Other manual transmission testing arrangements at the
               orignating office.

               Reference:  Bell System Practice 103-235-100

3.12      "99" Test Terminal
          In some stp-bystep offices the tens and units digits, 99, is a reverse battery test number.

3.13      Combination Milliwatt and Balance Test Line (New 100-Type
          Line)
          This is a new test termination that will be installed in all central offices to replace existing Noise and Balance - 900 Ohm or "quiet line" terminations (See 3.07).  Although all codes will eventually be equipped, a c following the 900 Ohm balance number in the appendixes indicates that the 100-type test line is the old type (i.e., termination only, no tone).  The advantages of the Combination Test Line are:
          a)   Gives a positive indication that a properly terminated
               Balance test line has been reached.
          b)   Allows both far-near loss and noise measurements to be
               made on one dial-up connection.

               The features of the Combination Milliwatt and Balance
               test line are as follows:
               a)   Trip machine ringing and return off-hook super-
                    vision.
               b)   Send 1000 hertz, one milliwatt test tone for 5.5
                    seconds.
               c)   Provide on-hook supervision for one second.
               d)   Return off-hook supervision and 900 Ohm
                    impedance termination until calling end
                    disconnects.

3.14      ATMS 105 - Automatic Transmission Measuring System (ATMS)
          Circuit (105-Type Test Line)
          Provides access to an ATMS responder used for automatic transmission measuring programs, such as ATMS and CAROT (Centralized Automatic Reporting on Trunks).  Information on Central Office responsibilities for CAROT can be found in Addendum 010-410-300 OB.



