\section{Changes in Version -07}

Since version -06, the following changes have been made. 

\begin{itemize}
\item Removed references to Internet Drafts.

\item Expanded URI definition to be independent of I-Ds. 

\item Clarified redirect behavior for {\BYE}. 

\item \header{Call-ID} mandatory for all requests to allow to match
requests with responses.

\item Clarified that {\INVITE} retransmit limit only applies if there
has been no provisional response.  Otherwise, call queueing is not
possible.

\item Removed open issues list.

\item Removed {\REGISTER} as special case of reliability mechanism.

\item Split out large syntax diagrams into figures to avoid empty space.

\item Abstract rewritten to reflect current protocol functionality.

\item Reorganized ``SIP Transport'' chapter to more clearly reflect
behavior for UDP and TCP.

\item Modified syntax for \header{Via} to include multicast address as a
parameter.

\item ``Ambiguous'' status code moved from 381 to 485, to give
precedence to other, more definitive 3xx responses. Also, 381 was the
only 3xx response that a proxy could not automatically recurse on.

\item Response merging made stricter, to avoid difficulties with merging
bodies and non-standard headers of 3xx responses.

\item {\REGISTER} {\MUST} have \header{Location} header.

\item Responses {\SHOULD} add a tag to the \header{To} header to allow
requests (e.g., {\BYE}) from several instances to be distinguished.

\item {\REGISTER} examples were missing \header{Via} headers.

\end{itemize}
