Problem with Retrieving some Attributes

Hi all I know that RADIUS server does AAA. Suppose that I have an active session (I made one with radclient). Now, I want to get an attribute of that session (for example, Calling-Station-Id); My problem is that I don't know what packet type should I send to RADIUS server to get attributes. My freeradius version: 2.0.4 in Debian Lenny. Thanks for any comment.