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Cisco Unity Connection

TIMG Does Not Forward Calls to Cisco Unity Connection

Document ID: 116939

Updated: Jan 09, 2014

Contributed by Scott Hills, Cisco TAC Engineer.

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Introduction

This document describes how to troubleshoot a Cisco T1 IP media gateway (TIMG) that does not forward an Invite to the Cisco Unity Connection. This means that the call is not connected to voicemail. This document describes the trace needed on the TIMG in order to troubleshoot the issue. It also provides examples of what you might encounter in the traces and offers a solution to the issue.

Problem

A private branch exchange (PBX) phone is linked to a Cisco Unity Connection voicemail service via a TIMG. A channel associated signaling (CAS) T1 line is used in order to connect the PBX to the TIMG. A serial RS-232 cable is used in order to carry the serial data (for example, Calling, Called, Call Forwarding Reason, and so on). The physical portion of the call is across the CAS T1C.

In this case, the PBX communicates with the calling data over the serial link via the message center interface (MCI). It can also communicate with the simplified message desk interface (SMDI) or the MD-110.

When the user makes a call from a PBX phone, it should forward to the Cisco Unity Connection voicemail server. Instead, the ringing continues, and the Unity Connection voicemail does not answer.

Troubleshoot Steps

In order to troubleshoot the issue further, enable the traces on the TIMG, and then make test calls and review the traces.

  1. On the TIMG, go to the Admin interface and choose Diagnostics > Trace/Logging.
  2. Beside Trace, click Configure. Cisco recommends that you turn on these traces:

      • Tel - check Prot and Event
      • Voip - Check Prot
      • Si - All
      • SiIP - All
  3. Click Submit.
  4. Beside Trace, click Start and make a test call after enough time has passed that you expect the call should have rolled to voicemail.
  5. Click Stop.
  6. Click Download in order to get the trace file.

The trace file displays similar to this list:

026:02.064 [Si        ] Prot     02
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     21
026:02.064 [Si        ] Prot     4A
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     31
026:02.064 [Si        ] Prot     31
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     32
026:02.064 [Si        ] Prot     39
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     34
026:02.064 [Si        ] Prot     32
026:02.064 [Si        ] Prot     32
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     31
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     32
026:02.064 [Si        ] Prot     33
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     30
026:02.064 [Si        ] Prot     37
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.064 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     30
026:02.096 [Si        ] Prot     30
026:02.096 [Si        ] Prot     31
026:02.096 [Si        ] Prot     38
026:02.096 [Si        ] Prot     36
026:02.096 [Si        ] Prot     39
026:02.096 [Si        ] Prot     38
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     20
026:02.096 [Si        ] Prot     03
026:02.096 [Si        ] Code     siSrvSerialInputEvent
026:02.096 [Si        ] Prot     From Serial: 02 30 21 4A 30 30 31 31 30 32 39
20 20 20
20 20 34 32 32 30 31 30 32 33 30 30 37 20 20 20 20 20 20 20 20 20 20 30 30 31 38
36 39 38 20 20 20 20 03 00
026:02.096 [Si        ] Code     siSrvPrcCpidFromSwitch ltn = 1029, src=, Dst =
1029, Redir = 8698, Reason = FwdAll
026:02.096 [SiIp      ] Code     sertrans_ServerLocateClient 1029
026:02.096 [SiIp      ] Code     sertrans_ServerLocateClient 1029=client1
026:02.096 [SiIp      ] Code     _TaskMainClientReceive received data 516
026:02.096 [Si        ] Code     serial_client_cb
026:02.096 [Si        ] Code         SI_TYPE_CPID 1029:FwdAll (->1029->8698)
026:02.096 [Tel-5     ] Code     GetChannelFromLogicalChannelNum LogicalChanNum 4
span 0 channel 5
026:02.096 [Tel-5     ] Code     t1casReportNewCpid
026:02.096 [Tel-5     ] Event    Cpid (,->1029,->8698,) (FwdAll)
026:02.096 [Tel-5     ] Warn     t1casReportNewCpid err: no call for cpid
026:02.096 [Tel-5     ] Code     t1casReportNewCpid saving pre-call cpid for serial
007:57.072 [VoIP      ] Prot     

Look at these lines:

026:02.096 [Si        ] Prot     From Serial: 02 30 21 4A 30 30 31 31 30 32 39
20 20 20
20 20 20 34 32 32 30 31 30 32 33 30 30 37 20 20 20 20 20 20 20 20 20 20 30 30 31
38 36 39 38 20 20 20 20 03 00

026:02.096 [Si        ] Code     siSrvPrcCpidFromSwitch ltn = 1029, src=, Dst =
1029, Redir = 8698, Reason = FwdAll

The first line is the raw data from the PBX. The next line translates the raw data to a more usable format for the TIMG. This verifies that data comes across the serial cable from the PBX.

Find this line in the trace:

026:02.096 [Tel-5     ] Warn     t1casReportNewCpid err: no call for cpid

Notice that there is no Session Initiation Protocol (SIP) invite generated to the Cisco Unity Connection. The Warn message indicates that no call comes into the TIMG from T1 CAS to go with the serial data. Without both, the TIMG does not generate a SIP invite for the call to the Cisco Unity Connection, which causes the phone to ring continuously.

Solution

The most likely cause of this issue is with the CAS T1. In some cases, the signaling on the TIMG does not match that of the PBX. The PBX configuration for T1 should be compared to the configuration on the TIMG.

On the TIMG choose Configuration > TDM > T1/E1. Check the Settings check box under Line Settings, T1 Line, and T1 CAS Protocol.

Related Information

Updated: Jan 09, 2014
Document ID: 116939