Hi, I have a problem with the SIP message REFER. I initiate a conference by entering into a conference room, and then I want Freeswitch to add a new participant. According to the RFC 4579, I sent a REFER message to Freeswitch to add the new participant and I get back a NOTIFY with sipfrag 403 forbidden I'm working with virtual IP adresses and I'm working only in local Below is the REFER message I send REFER sip:3000@192.168.20.3:6060 SIP/2.0 Via: SIP/2.0/UDP 192.168.20.4:7000;branch=z9hG4bKg4534 Max-Forwards: 70 To: <sip:3000@192.168.20.3:6060>;isfocus From: <sip:1000@192.168.20.4:7000>;tag=1832665346 Call-ID: jbDaf1W7hQtswyvf CSeq: 1 REFER Contact: <sip:1000@192.168.20.4:7000> Allow: INVITE,BYE,REGISTER,ACK,OPTIONS,CANCEL,INFO,PRACK,REFER,MESSAGE,PUBLISH Allow-Events: REFER Accept: application/sdp, message/sipfrag Refer-To: <sip:1001@192.168.20.3:5031;method=INVITE> Supported: timer, replaces, path Content-Length: 0 and here is the siptrace of FS recv 466 bytes from udp/[192.168.20.3]:7000 at 13:21:45.621109: ------------------------------------------------------------------------ REFER sip:3000@192.168.20.3:6060 SIP/2.0 Via: SIP/2.0/UDP 192.168.20.3:7000;rport;branch=z9hG4bKg4534 Max-Forwards: 70 To: <sip:3000@192.168.20.3:6060>;isfocus;tag=g2y4Btme55Fje From: <sip:1000@192.168.20.3:7000>;tag=1832665346 Call-ID: jbDaf1W7hQtswyvf CSeq: 476 REFER Contact: <sip:1000@192.168.20.3:7000> Allow: INVITE,BYE,REGISTER,ACK,OPTIONS,CANCEL,INFO,PRACK,REFER,MESSAGE,PUBLISH Refer-To: <sip:1001@192.168.20.3:5001> Supported: replaces Content-Length: 0 ------------------------------------------------------------------------ 2015-08-07 13:21:45.615060 [DEBUG] switch_core_session.c:1061 Send signal sofia/internal/1000@192.168.20.3 [BREAK] 2015-08-07 13:21:45.615060 [DEBUG] switch_core_session.c:978 Send signal sofia/internal/1000@192.168.20.3 [BREAK] 2015-08-07 13:21:45.615060 [DEBUG] sofia.c:7799 Process REFER to [ 1001@192.168.20.3] send 722 bytes to udp/[192.168.20.3]:7000 at 13:21:45.624429: ------------------------------------------------------------------------ SIP/2.0 202 Accepted Via: SIP/2.0/UDP 192.168.20.3:7000;rport=7000;branch=z9hG4bKg4534 From: <sip:1000@192.168.20.3:7000>;tag=1832665346 To: <sip:3000@192.168.20.3:6060>;isfocus;tag=g2y4Btme55Fje Call-ID: jbDaf1W7hQtswyvf CSeq: 476 REFER Contact: <sip:3000@192.168.20.3:6060;transport=udp> Expires: 60 User-Agent: FreeSWITCH-mod_sofia/1.4.20+git~20150701T115426Z~0ae8ee7f8f~64bit Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY, PUBLISH, SUBSCRIBE Supported: timer, path, replaces Allow-Events: talk, hold, conference, presence, as-feature-event, dialog, line-seize, call-info, sla, include-session-description, presence.winfo, message-summary, refer Content-Length: 0 ------------------------------------------------------------------------ 2015-08-07 13:21:45.615060 [ERR] sofia.c:8297 Cannot Blind Transfer 1 Legged calls send 888 bytes to udp/[192.168.20.3]:7000 at 13:21:45.624580: ------------------------------------------------------------------------ NOTIFY sip:1000@192.168.20.3:7000 SIP/2.0 Via: SIP/2.0/UDP 192.168.20.3:6060;rport;branch=z9hG4bKgNeKBK5H869jQ Max-Forwards: 70 From: <sip:3000@192.168.20.3>;isfocus;tag=g2y4Btme55Fje To: <sip:1000@192.168.20.3>;tag=1832665346 Call-ID: jbDaf1W7hQtswyvf CSeq: 79137188 NOTIFY Contact: <sip:3000@192.168.20.3:6060;transport=udp> User-Agent: FreeSWITCH-mod_sofia/1.4.20+git~20150701T115426Z~0ae8ee7f8f~64bit Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY, PUBLISH, SUBSCRIBE Supported: timer, path, replaces Event: refer;id=476 Allow-Events: talk, hold, conference, presence, as-feature-event, dialog, line-seize, call-info, sla, include-session-description, presence.winfo, message-summary, refer Subscription-State: terminated;reason=noresource Content-Type: message/sipfrag;version=2.0 Content-Length: 23 SIP/2.0 403 Forbidden ------------------------------------------------------------------------ send 888 bytes to udp/[192.168.20.3]:7000 at 13:21:46.625031: ------------------------------------------------------------------------ NOTIFY sip:1000@192.168.20.3:7000 SIP/2.0 Via: SIP/2.0/UDP 192.168.20.3:6060;rport;branch=z9hG4bKgNeKBK5H869jQ Max-Forwards: 70 From: <sip:3000@192.168.20.3>;isfocus;tag=g2y4Btme55Fje To: <sip:1000@192.168.20.3>;tag=1832665346 Call-ID: jbDaf1W7hQtswyvf CSeq: 79137188 NOTIFY Contact: <sip:3000@192.168.20.3:6060;transport=udp> User-Agent: FreeSWITCH-mod_sofia/1.4.20+git~20150701T115426Z~0ae8ee7f8f~64bit Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY, PUBLISH, SUBSCRIBE Supported: timer, path, replaces Event: refer;id=476 Allow-Events: talk, hold, conference, presence, as-feature-event, dialog, line-seize, call-info, sla, include-session-description, presence.winfo, message-summary, refer Subscription-State: terminated;reason=noresource Content-Type: message/sipfrag;version=2.0 Content-Length: 23 SIP/2.0 403 Forbidden ------------------------------------------------------------------------ send 888 bytes to udp/[192.168.20.3]:7000 at 13:21:48.626014: ------------------------------------------------------------------------ NOTIFY sip:1000@192.168.20.3:7000 SIP/2.0 Via: SIP/2.0/UDP 192.168.20.3:6060;rport;branch=z9hG4bKgNeKBK5H869jQ Max-Forwards: 70 From: <sip:3000@192.168.20.3>;isfocus;tag=g2y4Btme55Fje To: <sip:1000@192.168.20.3>;tag=1832665346 Call-ID: jbDaf1W7hQtswyvf CSeq: 79137188 NOTIFY Contact: <sip:3000@192.168.20.3:6060;transport=udp> User-Agent: FreeSWITCH-mod_sofia/1.4.20+git~20150701T115426Z~0ae8ee7f8f~64bit Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY, PUBLISH, SUBSCRIBE Supported: timer, path, replaces Event: refer;id=476 Allow-Events: talk, hold, conference, presence, as-feature-event, dialog, line-seize, call-info, sla, include-session-description, presence.winfo, message-summary, refer Subscription-State: terminated;reason=noresource Content-Type: message/sipfrag;version=2.0 Content-Length: 23 SIP/2.0 403 Forbidden Thanks for your help.