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PassMark ModemTest - ITU V.56 ter testing


ITU-T was created on 1 March 1993, replacing the former International Telegraph and Telephone Consultative Committee (CCITT) whose origins go back to 1865. The public and the private sectors cooperate within ITU-T for the development of standards that benefit telecommunication users worldwide.

The ITU develop recommendations (standards) for the various fields of international telecommunications. One of these standards is the V.56 ter standard, the title of the standard is, "Test procedure for evaluation of 2-wire 4 kHz voiceband duplex modems". The standard is publicly available from the ITU web site but last time we looked the ITU was asking 89 CHF (Swiss Francs) for it. The standard contains descriptions of various tests that need to be carried out in order for a modem to be compliant with the V.56 standard. A lot of these tests are based on the transfer of various test files between two modems while simulating various different line conditions (e.g. International telephone lines, local lines, lines with interference, etc..).

Because of the need to simulate various line conditions and the large number of tests that are required, these tests will normally only be done by larger organization who have the resources to purchase the necessary telephone exchange simulator hardware.

If you are a home user, it might be best to skip this page and just use the standard ModemTest options.

How ModemTest can help

The following table shows the data transfer files required for various tests in the ITU-T V.56 ter standard. (Based on version 08/96 of the ITU-T V.56 ter recommendation). The ModemTest software can be used to complete these tests.

Test data file (specification reference)

Description of test

1X04.TST (6.1.2)

One-way transfer – send 1X04 test file from the Master to the Slave. This is used in test 6.1.2 of the ITU-T v.56 ter specification.

1X30.TST (6.2.5)

As above, for test file 1X30. Reference 6.2.5.

2X10.TST (6.1.1, 6.2.5)

As above, for test file 2X10. Reference 6.1.1 & 6.2.5.

3X06.TST (6.2.5)

As above, for test file 3X06. Reference 6.2.5.

4X04.TST (6.2.5)

As above, for test file 4X04. Reference 6.2.5.

5X16.TST (6.2.5)

As above, for test file 5X16. Reference 6.2.5.

FOX message - with delay (6.3.2)

As above, for set number of FOX messages with 30 milliseconds of delay. Reference 6.3.2.

FOX message – with no delay (6.4.5)

As above, for FOX message with no delay. Reference 6.4.5.


1X30.TST – two way transfer (6.2.6)

Two-way transfer – send 1X30 test file from the Master to the Slave and from the Slave to the Master. Both will commence on connection. This is used in test 6.2.6 of the ITU-T v.56 ter specification.

2X10.TST – two way transfer (6.2.6)

As above, for test file 2X10.TST. Reference 6.2.6.

3X06.TST – two way transfer (6.2.6)

As above, for test file 3X06.TST. Reference 6.2.6.

4X04.TST – two way transfer (6.2.6, Annex A)

As above, for test file 4X04.TST. Reference 6.2.6.

5X16.TST – two way transfer (6.2.6)

As above, for test file 5X16.TST. Reference 6.2.6.


Download ModemTest ITU test data files

Download data transfer files (473KB, zip file)


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