Step 1 Capture network data packets on the SBC to analysis the call process.
Based on the analysis of the data packets for failed calls, the SBC did forward the invite message sent from the U1930 to the destination phone, as shown in .
Figure 1-1 Capturing network data packets on the SBC
Step 2 Analyze the data packets for the cause of failing to transfer the invite message.
The failure cause is that the SBC considers the destination port to be unreachable, as shown in #EN-US_TOPIC_0005932929/fig33311959222532.
Figure 1-2 Analyzing the data packets
Step 3 Send the data packets to New Rock's SBC engineers for further analysis. The failure cause may be that the SBC port connected to the phone has been updated. The timeout period for a phone to register with the SBC is 1800s. If the phone does not have any calls or send any registration messages to the SBC within 1800s, the port connected to the phone will be updated on the SBC.
Step 4 Check the registration timeout period for the phone. The period is defaulted to 3600s, which exceeds the registration timeout period configured on the SBC.
Step 5 Change the registration timeout period to 1800s.
After the change, the fault does not occur any more.