I guess that makes you pioneers when it comes to preconditions settings. Don’t assume that the fact that you don’t get an answer means that we ignore you.
The readers of the list propably doesn’t know since preconditions is a feature that isn’t used a lot.
In general, Kamailio is not involved in offer/answer setup - it’s a proxy that just forwards sdp to the caller and another one back from the callee. In some cases, Kamailio will manipulate the SDP in transit.
Let this issue be closed and discuss further on the mailing list. /O