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Knowledge Base

SoftCo didn’t detect busy tone signal lead to the called phone under SoftCo has been ringing

Publication Date:  2012-10-08  |   Views:  174  |   Downloads:  0  |   Document ID:  EKB1000016720


Issue Description

Caller using a mobile phone, through the AT0 relay incoming, the called is a phone number under SoftCo; When the called ringing (didn’t off-hook) caller called hang up, after hanging up the phone will continue to ring for about 1 minute. 

Alarm Information


Handling Process

1. Directly connected a POTS telephone to AT0 relay line, using the same method and make a call again. The caller hang up, POTS telephone ringing immediately stop, is able to check the busy tone signal, so the ringing will immediately stop.
2. Adjust the gain:
      With these two commands:
      config modif at0 card slot 2 portinboard 0 dagain 6 adgain 12
      config modif at0 card slot 2 portinboard 0 fskgain 10

Note: adjust the gain, the incoming gain adgain and outgoing gain dagain must adjust at the same time, or even perform adjust the gain command successful but no effect.
Adjust the gain, the fault is not eliminated.

3. By an ordinary analog telecommunications line to ground, fault problem disappeared; use other grounding modes, failure will not disappear. This is due to line interference current is too large, results in unable to detect the ground signal. Made the analog line to ground, the equivalent of the ATU veneer ground, problem can be solved.

Root Cause

1.The received busy tone signal amplitude is too low. The busy tone signal that can be detected by SoftCo is in the range of -10 ± 3db, because the signal energy is too low so our company SoftCo can not recognize.
2. AT0 relay modules large affected by static electricity, the device is not grounded or not grounded intact.


1. You can try directly let ATU veneer grounding that should also be able to solve the problem.
2. AT0 relay modules affected by static electricity, you need to ensure that the ground is in good condition, veneer screws must be tightened to ensure good contact with the veneer and cable.