Hi There, I use FS as proxy to handle a call with REFER to. My question is when get a REFER request, how to do the Transfer regarding the REFER TO before hangup the current channel. My mean before send back the NOTIFY, do the INVITE (based on REFER TO), when the INVITE is 200 OK, then send back NOTIFY. my logs: 11:24:14.141700 [DEBUG] sofia.c:6616 Process REFER to [11004@111.22.33.1] 11:24:14.141700 [DEBUG] switch_ivr.c:1773 (sofia/external/6175552222@12.13.14.15) State Change CS_EXECUTE -> CS_ROUTING 11:24:14.141700 [DEBUG] switch_core_session.c:1287 Send signal sofia/external/6175552222@12.13.14.15 [BREAK] 11:24:14.141700 [DEBUG] switch_core_session.c:830 Send signal sofia/external/6175552222@12.13.14.15 [BREAK] 11:24:14.141700 [NOTICE] switch_ivr.c:1779 Transfer sofia/external/6175552222@12.13.14.15 to XML[11004@public] 11:24:14.161701 [DEBUG] switch_ivr_play_say.c:1682 done playing file local_stream://moh 11:24:14.161701 [DEBUG] switch_ivr_bridge.c:597 BRIDGE THREAD DONE [sofia/external/+18550000000@1.2.3.4:5060] 11:24:14.161701 [DEBUG] switch_ivr_bridge.c:622 Send signal sofia/external/6175552222@12.13.14.15 [BREAK] 11:24:14.161701 [DEBUG] switch_channel.c:2979 (sofia/external/+18550000000@1.2.3.4:5060) Callstate Change HELD -> HANGUP the Transfer to XML[11004@public] not DONE yet, the (sofia/external/+18550000000@1.2.3.4:5060) already Hangup, How to delay the Hangup after Transfer is done?