Symptoms

Scenario 1: The call from the carrier side to the command center does not ring.

Scenario 2: A agent phone calls a mobile phone. After 5 seconds, the mobile phone rings, and the mobile phone rings for 6 seconds. The fixed-line phone automatically hangs up. Then the mobile phone rings for 10 seconds and the mobile phone hangs up.

Cause

1.       Redundant routes are configured on the SBC.

2.       The corresponding route cannot be found for the call. As a result, both incoming and outgoing calls are abnormal.

Analysis

Scenario 1: Enable SIP signaling packet capture on both the USM and SBC. Call the carrier's mobile phone from the call center phone to capture signaling for analysis. USM analysis result: The USM receives the INVITE message from the IP phone but does not receive the 18X receipt message from the SBC after forwarding the message.

Scenario 2: Analysis result of the SBC: The SBC receives both the INVITE message and the receipt message (18x message) from the carrier side, but the 18x message is retransmitted.

Method introduction & Solution

1. Log in to the SBC by referring to the guide.

2. Delete redundant routes in the SBC.

Conclusion

Check the configurations that have been configured during delivery after the configurations are deleted and ensure that the configurations are cleared to prevent service problems caused by unresolved configurations.

The above scenarios are completed in the laboratory environment, only for case reference, not as the guidance basis for specific problems. If there are further questions. Please obtain the above log and send it to R&D or contact us with TAC support team.

Postscript

If you have any questions, welcome to reply and exchange, looking forward to your reply and good comments. thank you.