Hi All, I am using Kamailio 4.1 as SIP proxy and registrar with websocket and msrp modules. As a client I am using the JsSIP stack. The client can open websocket for SIP messages by calling "new WebSocket('ws://1.2.3.4:8000','sip')" with sip as a subprotocol, this works fine. But when the client tries to open a websocket for MSRP sessions using new WebSocket('ws://1.2.3.4:8000','msrp') in the browser log I see  the error 'WebSocket connection to 'ws://1.2.3.4:8000/' failed: Unexpected response code: 400' . For MSRP file transfer I am using the crocodile msrp lib.  The HTTP GET request of sent by the client is: GET / HTTP/1.1 Via: SIP/2.0/TCP 10.147.66.197:54818 Upgrade: websocket Connection: Upgrade Host: 192.168.144.48:8000 Origin: http://localhost Sec-WebSocket-Protocol: msrp Pragma: no-cache Cache-Control: no-cache Sec-WebSocket-Key: gccXstTCf+egnPtufU2xng== Sec-WebSocket-Version: 13 Sec-WebSocket-Extensions: x-webkit-deflate-frame User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36 Cookie: PHPSESSID=pdlbnc3h24i5r8rdg1979tino2 In the log of Kamailio I see these lines: 11(2114) WARNING: websocket [ws_handshake.c:318]: ws_handle_handshake(): required headers not present 11(2114) DEBUG: sl [sl.c:288]: send_reply(): reply in stateless mode (sl) 11(2114) DEBUG: <core> [msg_translator.c:204]: check_via_address(): check_via_address(10.147.66.197, 10.147.66.197, 0) 11(2114) DEBUG: <core> [tcp_main.c:2320]: tcpconn_send_put(): tcp_send: send from reader (2114 (11)), reusing fd 11(2114) DEBUG: <core> [tcp_main.c:2556]: tcpconn_do_send(): tcp_send: sending... 11(2114) DEBUG: <core> [tcp_main.c:2590]: tcpconn_do_send(): tcp_send: after real write: c= 0x7f37ab162bd0 n=182 fd=8 11(2114) DEBUG: <core> [tcp_main.c:2591]: tcpconn_do_send(): tcp_send: buf= HTTP/1.1 400 Bad Request Via: SIP/2.0/TCP 10.147.66.197:54744 Sec-WebSocket-Protocol: sip Sec-WebSocket-Version: 13 Server: kamailio (4.1.1 (x86_64/linux)) Content-Length: 0 So, anyone has an idea whats the problem is? Thanks,   Medo