I use openser 1.0.1 and use rtp proxy for some cases other than nat option. At voice calls I do not have any problem. But When I try to send fax,it is unsuccesful. I investigated the logs and saw that, after the reinvites ( to take the session from g729 to G711u bypass mode ), the last OK message's SDP that is sending from openser to user agent is not correct.Etheral logs are attached.