[sr-dev] sdp info?

Hello, I am working on welcome announcement,I have to play an announcement in ekiga after an INVITE Message sent to kamailio.I require sdp information which should be edited as per welcome announcement,which file gives me sdp info of INVITE Message?? As per developer's guide, struct sip_msg should consist of struct sdp_info, but in kamailio code,it is no where present uder sip_msg. So,How would i get sdp information?? Thanks & Regards, Manjusha A. Integra Micro Software Services (P) Ltd.