Micro Seven Inc.®, model ST200, NEW, automatic telephone line tester, for digital measurement of loop voltage, loop current, ring signal, call progress tones, and frequency attenuation characteristic, distortion characteristics and random noise amplitude of audio signals between two telephone lines.

Copyrights Micro Seven, Inc.®, 2018


ST200 is the same size as our model LS15 in the above picture.




-two RJ11 jacks to input FXS interface

-measurement of loop voltage

-measurement of loop current

-measurement of ring signal amplitude and frequency with load and without load

-measurement of dial-tone amplitude

-testing DTMF/rotary-pulse dialing capability

-frequency attenuation characteristics of signal connection between two phone lines

-insertion loss measurement between two phone lines

-harmonic distortion and random noise amplitude measurement

-RS232 interface

-automatic test software



Automatic test software via RS232 interface:

Software: compatible to Windows

Automatic test sequence 1:

1.    check loop voltage over Vmin

2.    check loop current over Imin

3.    check ring signal for minimum amplitude and within frequency range

4.    check dial-tone for Vmin

5.    check for minimum DTMF dialing amplitude

6.    check signal insertion characteristics between two phone lines and check frequency attenuation characteristics of several frequencies and minimum amplitude

7.    check for random noise amplitude-the end of automatic test sequence 1

Automatic test sequence 2: (2-line back-to-back basic calling test)

1.    Call from line 1 to line 2. Send “Automatic test sequence 2-(date) (time) start” at RS232 interface.

2.    Line 2 answers the incoming ring signal and goes off-hook. Transmit answer tone. Send “receive ring signal at line 2, answer with off-hook, and transmit answer tone.” at RS232 interface.

3.    Receive answer tone and check within its range and amplitude at line 1. Send “ receive the tone at line 1 Ok”.

4.    Transmit answer tone at line 1. Receive answer tone and check within its range and amplitude at line 2. Send “Send answer tone back-----“

5.    Both lines go on-hook, send “signal transmission/reception success” at RS232 interface.

6.    Pause time of between 0 and 2 minutes”

7.    go through the same sequence of 1 and 5 originating a call at line 2 to line.

8.    Pause time of between 0 and 2 minutes

Screen of preliminary software is shown below:

Operating power input: 117V AC nominal, 230V AC custom build

 Micro Seven, Inc. ®

1095-K N.E. 25th
Hillsboro, OR, U.S.A.

phone: 503-693-6982
fax: 503-693-9742

Home Page: www.microseveninc.com

Email: sales@microseveninc.com

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