[Serusers] radius accounting capabilities with SER

Hello all, I have been going through the archives, but could not see any question on the same subject, so here it goes: After putting together a freeradius server and a CVS version of SER, the server can authenticate users using RADIUS. Now I'm trying to do accounting on certain events, mainly calling and sending messages between clients. Radius Accounting Start messages are created and sent to the RADIUS server when calling from one User Agent to the other, but no Stop messages are created once the two end points finish the conversation. SIP dialogs are record-routed, so SER is able to see all the transactions. My questions are: - What triggers the generation of radius accounting requests? - Can we configure these triggers somehow (on a per method/filter basis)? Any hints on this would be very appreciated. Jaime