[Freeswitch-dev] sending custom SDP in 200 OK

I have written a application called mod_custom. In this module i would like to set a user-defined RTP port and IP adress and then send the 200 OK (answer the call). But i see that, before my application is invoked, 183 message is sent with SDP. And i didnot find a way to either disable sending 183 and just send 180 OR modify the SDP to be sent in 200 OK. please help. Rajk