Hi List Greetings

How do we authorize users using FreeRADIUS such as way that ClientA can only use VOIP service, ClientB mail only, ClientC internet only and so on ?

Do we do by using some attributes ? or possible in unlang only ?

i do not have logical diagram in my mind, how would i achieve that, using port numbers of services ?

Could someone help me to understand ? 

--THKS  --RM