id(int,auto) username(string) domain(string) contact(string) received(string,null) path(string,null) expires(int) q(double) callid(string) cseq(int) last_modified(int) flags(int) cflags(string,null) user_agent(string) socket(string,null) methods(int,null) sip_instance(string,null) attr(string,null) 
