Logging data packet count to accounting table?

Hello, I'm using FreeRadius for authenticating DSL users. Additional to the Input- and Output octets I would like to log the transferred packet count for the actual DSL session. I need this information to generate statistics - and in past i got this information from another (not local) Radius server, so I think, it should be not impossible. I didn't found any variables where this info is avaliable - is there any possibility to get this information? Thank you! Max (Wuppertal, Germany)