Users on Different IADs Cannot Hear Each Other During a Voice Call

Publication Date:  2015-07-14 Views:  141 Downloads:  0
Issue Description
Network: IAD132E(T)-SoftCo9500 (MRU board)-IAD132E(T)

 SoftCo9500: V100R002C04SPC700
 IAD132: V300R001C04SPC800

Users 8970 and 8985 are on different IADs connected to the same SoftCo. When one user makes a voice call to the other user, the calling party cannot hear the ringback tone but the called party's phone rings. When the called party picks up the phone, neither of the parties can hear each other. The IP addresses of the two IADs are and respectively.
Handling Process
Step 1 Capture and analyze the network packets sent and received by both parties, as shown in .

Figure 1-2 Analyzing network packets

From the network packet analysis, an exception occurs during the signaling establishment between the calling number 8970 and called number 8985. When the calling party sends an INVITE message, the called party returns a 180 message (indicating that the called party's phone rings). However, after passing through the SoftCo, the 180 message changes to a 183 message. The calling party considers that it does not send all required messages and sends the INFO message repeatedly. The called party returns the 200 OK message repeatedly but cannot receive any response from the calling party. Finally, the SoftCo considers that an unknown error occurs and sends a 500 message to the calling party.

Step 2 Analyze SoftCo call logs.

The following error information is found:

[2013-08-07 09:00:40.49][Rm.c 19977] [Rm.c19977]RM_MRSPlayTone:Esn=1094,CallID=3271,ComponentID=1Y  
[2013-08-07 09:00:40.49][Rm.c 20047] [Rm.c 20047] RM_MRSPlayTone::GDSP channel = -1
[2013-08-07 09:00:40.49][ipcm.c 1530]message send failed! m
[2013-08-07 09:00:40.49][ipcm.c 2078]ERROR: IPCM_PlayTone, CMD send failed! PID:83, ESN:1094, CRNo:3271? 
[2013-08-07 09:00:40.49][sipusm.c 1455][dwUsn= 1094] [dwCRNo= 3271]SIPUSM_SetCRState: from [ EN_SIPUSM_CR_OVERLAPSEND ] to [ EN_SIPUSM_CR_OVERLAPSEND ]? 
[2013-08-07 09:00:40.49][sipusm.c 17543][dwUsn= 1094] SIPUSM_MRSMsgProc, CRNO:3271
According to the preceding information, voice playback fails on the SoftCo. The possible cause is that the internal RBT service is enabled.

Step 3 Run the show board command on the SoftCo. The following information is displayed, indicating that the MRU board is used:
[%SoftCo9500(config)]#show board 


Slot Type State     Actual-board 
---- ---- --------- ------------ 
0    MCU  Slave_OK  MCU          
1    MCU  Master_OK MCU          
2    ---  ---       ---          
3    ---  ---       ---          
4    ---  ---       ---          
5    ---  ---       ---          
6    ---  ---       ---          
7    DTU8 OK        DTU8         
8    ---  ---       ---          
9    MRU  OK        MRU          

------- Matched record number : [10] -------

Step 4 Run the show subpbx command on the SoftCo. The following information is displayed, indicating that the internal RBT service is enabled:
[%SoftCo9500(config)]#show subpbx 

SubPbx info

NO. SubPBX Name   MaxTkcCount UsedTkcCount OfficeSelectCode MaxConfRoom UsedConfRoom 
--- ------------- ----------- ------------ ---------------- ----------- ------------ 
0   defaultsubpbx 100         2            0                32          3            
MaxConfSeat UsedConfSeat InterConfDn OutConfDn RegGroupID OuterCRBTSwitch OutSubpbxDn 
----------- ------------ ----------- --------- ---------- --------------- ----------- 
32          9            000         000       0          OFF             none        
InterCRBTSwitch ColorRingIndex 
--------------- -------------- 
ON              0 

Step 5 Run the config modify subpbx no 0 intercrbtswitch off command to disable the internal RBT service. The problem is solved.

Root Cause
The MRU board does not support the internal RBT service.
You are advised to check the type of the media resource board before enabling the internal RBT service. On SoftCo9500, only the MRS board supports the internal RBT service. If you enable the internal RBT service on the MRU board, unknown errors may occur. If you need to enable the internal RBT service but the MRU board is used, replace the MRU board with the MRS board.