Networking: PSTN-U1911-IAD-Analog phone
PSTN User Hears the Normal Ringing Tone After the User Calls a Busy PBX User
1. According to the fault details, the fault occurs only in a scenario where a PSTN user calls an intra-PBX user. When intra-PBX users call each other, the calling process is normal.
2. Capture the debug log on the U1911. It is found that the U1911 has returned an ALERTING message with a prompt tone.
3. The debug log also shows that the prompt tone is 140, which is a normal busy tone.
4. According to the preceding analysis, it is suspected that the PSTN does not support tone playing from the PBX. Therefore, software parameter 308 is modified so that an error code is sent to the PSTN, instructing the PSTN to play the tone.
5. Tests find that the busy tone is played normally.