\begin{syntax}
SIP-URL	        & = & "sip:" [ userinfo "@" ] hostport \\
                &   & url-parameters [ headers ]\\
userinfo        & = & ; {\rm defined in \cite{rfc2396}}\\
hostport        & = & ; {\rm defined in \cite{rfc2396}}\\
url-parameters  & = & *( ";" url-parameter) & \\
url-parameter   & = & transport-param $|$ user-param $|$ \\
                &   & ttl-param $|$ maddr-param $|$ tag-param $|$ other-param\\
transport-param & = & "transport=" ( "udp" $|$ "tcp" ) & \\
ttl-param       & = & "ttl=" ttl     & \\
ttl             & = & 1*3DIGIT       & {\rm ; 0 to 255}\\
maddr-param     & = & "maddr=" maddr & \\
maddr           & = & IPv4address    & {\rm ; multicast address}\\
user-param      & = & "user=" ( "phone" ) & \\
tag-param       & = & "tag=" UUID & \\
other-param     & = & *uric\\
headers         & = & "?" header *( "\&" header )\\ 
header          & = & hname "=" hvalue\\
hname           & = & *uric\\
hvalue          & = & *uric\\
uric            & = & ; {\rm defined in \cite{rfc2396}}\\
digits          & = & 1*DIGIT\\
\end{syntax}
