SIP phone interoperability

I am interested in the working group's position on interoperability between
WebRTC and standards based SIP phones.  There are several possible hurdles
like DTLS and SDP profile.  Is it the scope of the working group to make
WebRTC interoperable with SIP phones and if so is it the working group's
intent to require a mediating gateway in the media stream, are you expecting
the phone vendors to support WebRTC media in phones, or other?   Are there
any hard/soft phones available that can communicate with a WebRTC client in
e.g. Chrome or Firefox?

 

Thanks

--martin