Account in FreeRadius

I am using freeRadius in project of Voip in the system AAA. And I use with NAS the GnuGk, the OpenSER and Asterisk. GnuGK - Authorize / Authenticate / Account Openser - Authorize / Authenticate and I am putting Account Asterisk - I am putting Account But I don`t like put each one in the same table - table raddacct. I Would like insert GnuGK in table radacct, Openser in table radacctser and Asterisk in table radacctasterisk . Openser and Asterisk send a flag with a information TYPE-NAS in yours Account with Radius. GnuGK not, but if TYPE-NAS null, NAS is GnuGK. But I don`t know like create this condicional in FreeRadius. If possible, I would like if some one help me. ok? very thanks, Thiago Resende.