Use Lync Server 2010 Logging Tool.
You can run the Lync Server 2010 Logging Tool on the other computer by installing the Lync Server administrative tools on that computer. OCSLogger.exe is the file that runs Logging Tool, which by default is installed to %ProgramFiles%\Common Files\Microsoft Lync Server 2010\Tracing.
In order to best diagnose issues with SIP you must select the above Logging Options Components:
- S4 -> Level: All and Flags: All_Flags
- SIPStack -> Level: All and Flags: All_Flags
Start and Analyze log files.