Codec specification alternatives?

Greetings!

The IMAP Voice extensions presents numerous alternatives for client's
specification of the codec, it wishes to receive from the server. I'd
like to learn of the current situation, namely:

1) Is there any work being done in order to elliminate some options
and standardize other(s)?
2) Has anybody implemented one of the alternatives listed, and if so,
which one?

After some thought, we decided to use the client capability mechanism
for codec specification. Assuming we're not the only ones, we'd like
to coordinate the effort of specifying this extension formally in
order to create a sort of 'de facto' standard which may (or may not)
be adapted at later stage by additional parties.

Also, what is the status of the rest of the draft? Any work planned to
be done during the next IETF meeting?

--
Dmitry Rubinstein