A call's media mode as stated in dwMediaMode in LINECALLINFO and a media mode message (LINE_MONITORMEDIA) sent from the service provider to the application can and often will differ. An application could use lineMonitorMedia to enable monitoring for particular media modes, and use any resulting LINE_MONITORMEDIA messages as guidance in determining what the calling party might be probing for or what the unknown application should probe for first. LINE_MONITORMEDIA messages report events on the line (such as probes being received from the remote station) and not "hard" decisions about media modes. When an application determines that a call involves a particular media mode, it calls lineSetMediaMode to update dwMediaMode in LINECALLINFO and inform other applications of this update.