different cost for different services

Hello everybody, I'm going to set-up different services that are going to use the same freeradius server and accounts. So actually I have user X that with the same username/password can use service A and service B connecting from different NAS; services have a different cost to the end user. Is it possibile to configure freeradius in such a way where, for me, cost means a different amount of seconds? Thanks, sub