The PSTN cannot detect any signals and considers that the call has ended.
According to the fault symptom, ask the channel to perform the following test:
1. Make intra-office calls (excluding the AT0 impact). The test result is OK.
2. Directly connect a phone to the AT0 line without using the U1930 and make calls. The test result is OK.
3. After the preceding steps, incoming and outgoing calls through the U1930 still automatically end after they are connected for about 3 minutes. Once in another office, when eSpace 7910 IP phone users make calls to mobile phones through Huawei PBX, sometimes calls cannot be connected. That fault is rectified after the IP phones are upgrade to V100R001C01SPC700. Ask frontline engineers to upgrade the IP phones to V100R001C01SPC700 and test again. The following figure shows the test result.
4. According to frontline engineers, this fault does not occur on the U1930 V100R001C01SPC600. When U1930 is upgraded to V100R001C01SPC800, if no one talks for a period of time during a call, the call automatically ends after about 3 minutes. However, if the calling and called parties talk, the call will not be ended.
5. It is suspected that the voice activity detection (VAD) function is enabled by default for the AT0 trunk on the U1930 V100R001C01SPC800. Log in to the U1930, and run the following command:
show at0 silence detection parameter
The SilenceDetEnable value is 1, indicating that the VAD function is enabled.
6. Run the following command to disable the VAD function:
config at0 silence detection switch off
7. Test again. Calls will not automatically end when no one talks for a long period of time after the calls are connected.