Hi, all. The FreeSWITCH version is 1.6.2. I use proxy mode for a call first, because this mode might result in p2p call. but later, I want the call to join a conference, so I use "uuid_media off uuid" and "uuid_media uuid" to put the media to be sure pass FreeSWITCH. and then use “uuid_transfer uuid -both 3000” to join a conference. but FreeSWITCH report error and hangup, the log is as below: 3085747e-94d1-11e5-a40d-d5b76af33443 2015-11-27 14:36:49.857633 [ERR] switch_core_io.c:1423 Codec RAW Signed Linear (16 bit) encoder error! 3085747e-94d1-11e5-a40d-d5b76af33443 2015-11-27 14:36:49.857633 [DEBUG] conference_loop.c:1391 Channel leaving conference, cause: NONE 3085747e-94d1-11e5-a40d-d5b76af33443 2015-11-27 14:36:49.877633 [DEBUG] switch_core_codec.c:246 sofia/internal/1011@180.110.180.234:64052 Restore previous codec PROXY:0. The log shows that proxy mode can not be used in conference. so I think the solution is that before join conference, I should set the call’s media handling mode to default. but I do not know how to do that. Can someone help me please. Thanks.