system manager is for configuration purposes. SysMonitor can trace call and create log files ( should be installed with sys manager in C:\Program Files\Avaya\IP Office\Monitor\).
Click Ctrl+T (trace option) then untick all unnecessary options ( "call logging" is just enough for tracing calls).
Click Ctrl+L for setting log file.
Click Ctrl+W to start logging to file.
now you can search log files for certain phone number.
hope this helps!