// Based on Axis 1.1
import org.apache.axis.MessageContext;
import org.apache.axis.transport.http.HTTPConstants;
...
...
public class SomeService

 public string SomeMethod(String someInput)
{

//write your other codes here..
MessageContext context = MessageContext.getCurrentContext();
String callerIP = (String)context.getProperty(HTTPConstants.MC_REMOTE_ADDR);
//use the callerIP variable for tracking purpose..
...other code..
}

//based on Axis 1.3
import org.apache.axis.Constants;
import org.apache.axis.MessageContext;

....
....
MessageContext messageContext = MessageContext.getCurrentContext();
String ipAddress = messageContext.getStrProp(Constants.MC_REMOTE_ADDR);