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wrong configuration of AT0 paramaters leat to the FXO lines cannot be released

Publication Date:  2014-04-30 Views:  193 Downloads:  0
Issue Description
U1930 C01SPC900 version, connect to PSTN via FXO ports (AT0 trunk). After the mobile hung up the call, the FXO lines stuck in "busy" states. 
Alarm Information


Handling Process
U1900 provide the function of busy tone parameters automatically detection. steps as below:

1. Make an outgoing call via AT0 trunk (FXO ports), call from internal extersion to PSTN mobile.

2. Run command "show board slot <X>" to check which FXO port is busy. <X> is the slot number of OSU board. 
From the result (as below snip) we know this call is on FXO port 0.


3. Mobile pick up this call and then hang it up. Now the internal extension will hear the busy tone. Do not hung up the internal extension.

4. execute command " config start monitor osu tone slot 3 port 0 ". U1930 will begin to measure the busy tone parameters in background. 

5. Waiting for about  half a minute, then execute " config stop monitor osu tone ". The parameters will print on the CLI window immediately, as below snip.


6. From the result we know the parameters of the busy tone on this FXO ports are :

          On-time: [167, 213] ms
          Off-time: [175, 225] ms
          Frequency: [394, 446] Hz

7. Execute command " show tone detect parameter " to check the current settings of bust tone detection parameters.

8. From the result we know that the current busy tone detection parameters are: 

          On-time: [300, 400] ms
          Off-time: [300, 400] ms
          Frequency: [425, 475] Hz

9. Now the problem is clear: the busy tone detection settings on U1930 do not match with the busy tone in that country. Need to modify the parameters of busy tone detection by below commands:

        config tone detect parameter tonetype busy1 frequency1min 394 frequency1max 446 ontime1min 167 ontime1max 213 offtime1min 175 offtime1max 225

10. Test again, after the PSTN mobiel hang up, the FXO port was released immediately. Now the problem has been solved.

11. Execute "save " to save the configuration.
Root Cause
Basic Principle of AT0 trunk (FXO ports):

      For a call via AT0 trunk, if the mobile hung up the call, operator will send busy tone to the FXO ports of U1930. U1930 will release this line when recognising the busy tone sent to one FXO port.

      But because the parameters of busy tone is totally different in different countries, In most countries we must change the detection parameters of busy tone  on U1900.
Modification of busy tone decetion parameters is needed in most projects which U1900 connect to operator via AT0 trunk ( FXO port ) .