Hi all i use kamailio sip proxy, its version is: [root@localhost kamailio]# /opt/sbin/kamctl fifo version Server:: kamailio (3.0.1 (i386/linux)) i use 2 xlite softphones to register to sip proxy and register successfull and use xlite make call to another xlite softphone and get 488 Not Accept Here all sip proxy, xlite softphones in the same LAN please help to fix in the sip proxy that doesnt check the SDP Thank you Ha` and the debug log: DEBUG: tm [t_reply.c:1059]: ->>>>>>>>> T_code=100, new_code=488 DEBUG: tm [t_lookup.c:1080]: DEBUG: t_check_msg: msg id=2 global id=2 T start=0xb60ae9f0 DEBUG: tm [t_lookup.c:1152]: DEBUG: t_check_msg: T already found! DEBUG: tm [t_reply.c:1549]: DEBUG: relay_reply: branch=0, save=0, relay=0 DEBUG: <core> [msg_translator.c:1876]:  old size: 500, new size: 440 DEBUG: <core> [msg_translator.c:1894]: build_res_from_sip_res: copied siz  ontent-Length: 0ull "SDP: Incompatible media format: no common codec."19-1--d87543-;rport=51020 &quot;Tốt hơn, thoáng gọn hơn, nhanh hơn -Trải nghiệm Yahoo! Mail mới hôm nay! http://vn.mail.yahoo.com&quot;