Hi to all,  I am trying to use FS to handle a 3-way call conference with REFER. A calls B, then puts B on hold and then calls C, then puts C on hold too, and calls conference room. After that A sends REFER to FS for B and C to move them to conference room. FS handles first REFER and transfers B leg to conference room correctly, but unexpectedly FS sends a BYE to A party for conference call too and terminated A party from conference with this :Reason: SIP;cause=601;text="ATTENDED_TRANSFER" I put this config in conference: <param name="conference-flags" value ="rfc-4579"/>   but did not help and FS does not any 'isfocus' to OK contact header for A party.So is there any other config? or FS does not really handle Ad hoc conferencing based on RFC 4579. Thanks for your help. Regards,Hossein