I work for a telecom installer and we are deploying asterisk-based telephony systems.
To connect the PSTN accesses on our installations, we use gateways (beronet, patton, grandstream, etc.).
From my experience the RFC4733 (previously RFC2833) seems to be the default for trunk sip operators today. I think it’s a good thing to have DTMF in the media stream, because historically it’s media after all.
Hence my post to ask more people what the state of the art is and when you have the choice what kind of dtmf do you configure by default?