Symptom:
The U1911 connects to Siemens devices through the PRA trunk. When Siemens makes an incoming call to a U1911 subscriber, the called party is alerted about 12 seconds later.
Networking scenario:
U1960 ----- SIP Trunk ------ 1911 ----- PRA Trunk ----- Siemens gateway
Analysis process:
1. According to the analysis of the symptom reported on site, the called party can ring, indicating that the call can be sent to the U1911 through the Siemens device through the PRA trunk. The PRA trunk link should be normal.
2. Capture call logs on the U1930 for analysis.
3. According to the call logs provided by the onsite engineer, the U1911 considers that the called number is incomplete and calls the called number only after the digit collection times out.
4. Analyze the SETUP message sent by the Siemens device through the PRA trunk. It is found that Siemens does not carry the Sending Complete flag, indicating that digit collection is complete.
The following figure shows the normal SETUP message that carries Sending Complete.
On the U1911, the maximum length of the intra-office prefix is set to 32 digits because the length of the intra-office user number is not fixed.
Cause
The SETUP message sent by the Siemens device through the PRA trunk does not carry the Sending Complete flag, indicating that digit collection is complete.
5. The maximum number length of the prefix on the U1911 is large. Therefore, the U1911 determines that digit collection is complete and calls the called number only after the digit collection timer expires (12s).
Handling Procedure:
The number length on the U1911 is not fixed. Therefore, you are not advised to change the minimum and maximum number lengths on the U1911. It is recommended that Siemens devices modify the SETUP message to carry the Sending Complete flag.
Siemens devices modify the SETUP message to carry the Sending Complete flag.
