Networking:SoftCo 5816 -- SIP -- IAD132E(T)16O16S -- FXO port -- Carrier
When an external phone dials a number to make an incoming call to an internal extension, the extension rings but the call is not answered. After the external phone hangs up, the extension still rings.
Step 1 Record the busy tone using the DBWINon the FXO port of the IAD.
Step 2 Analyze the IAD DBWIN recording. It is found that the busy tone signals sent from the calling party comply with a certain foreign standard but does not comply with the national standard.
Step 3 Adjust the IAD busy tone detection scope and frequency based on the recording analysis.
TERMINAL(advanced-config)#dsp busytone_detect offtime1_min 300
TERMINAL(advanced-config)#dsp busytone_detect offtime1_max 340
TERMINAL(advanced-config)#dsp busytone_detect ontime1_min 300
TERMINAL(advanced-config)#dsp busytone_detect ontime1_max 340
TERMINAL(advanced-config)# dsp busytone_detect low_freq 425
Step 4 Test the service. It is found that the service is normal. The problem is solved.
The possible cause is that the calling party does not send busy tone signals to the called party or that the busy tone signals selected by the calling party's carrier do not comply with the national standard when the calling party hangs up.