Hi Ali,
I understand what you wanted to ask, but you didn't quite put it in correct words.
Kamailio server can act as a Radius client which means it can be integrated with a Radius Server. Kamailio itself is not a Radius server you may have to look for options opensource or propriety for Radius servers.
So a radius client provisioned SIP server can send AAA packets to a connected Radius server based on call start, end or custom packets, and communicate through AVPs and SIP Radius dictionary.
Hope that answers the question.
Cheers
Salman