[Serusers] Dropping 200-ok?

Hi list. I want to make an analisis at a 200-ok response from an INVITE. I implemented at ser 0.9.4 an "on_reply_route" to check if the 200-ok contains the SDP address of the gateway I want to connect. It its true, I let the 200-ok flows. If it´s not, I want to drop this and terminate the call (SIP ERROR or whatever). Here is the example ============= ------------- "A" =======> | "SER" | =========> "B" ------------- 1) "A" INVITEs "B" through SER 2) "B" says that its trying and ringing to "A" 3) User at "B" picks-up 4) I check the 200-ok at SER. If it´s ok, let it flow to "A". If it´s not, I want to drop it and terminate the call establishment. DO ANYBODY DID THAT OR CAN HELP ME WITH ANY CLUE/STARTING POINT? best regards to all. Ricardo Poppi.