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This topic describes how to analyze and rectify the fault where an intra-office user cannot hear the busy tone when an outer-office user hangs up.
Symptom
The unified gateway is connected to the PSTN through an AT0 trunk. When a PSTN user hangs up during a call with an intra-office user, the intra-office user cannot hear the busy tone.
Possible Causes
The possible causes are as follows:
ϒ⁄The configuration is incorrect at the carrier side. As a result, no busy tone is sent when the outer-office user hangs up.
ϒ⁄The AT0 trunk line is too long and signal attenuation occurs. As a result, the unified gateway cannot detect analog signal tones.
Procedure
1.Connect a phone to the AT0 trunk interface provided by the carrier and call the corresponding user line number using a PSTN number. Hang up after the call is connected. Then check whether the called party hears the busy tone.
ϒ⁄If the busy tone is heard, contact the peer end engineer to adjust the configuration.
ϒ⁄If no busy tone is heard, go to the next step.
2.If the AT0 trunk is used for connection, change the off-hook gain to check whether the fault is rectified.
ϒ⁄Run the show osu information slot slot command to check the current off-hook gain.
In the command output, txgain indicates the Tx gain and rxgain indicates the Rx gain.
ϒ⁄Run the config modify osu slot slot txgain txgain rxgain rxgain [startportno startportno number number] command to change the off-hook gain.
ϒ⁄Check whether the fault is rectified. If the fault is rectified, the troubleshooting process is complete. If the fault persists, go to the next step.
3.If the fault persists, collect detailed fault information and related logs, and submit them to the service provider. For details, see Collecting and Reporting Fault Information.
Parent Topic: AT0 Trunk Faults