I have deployed it (admittedly on an old C3800 gateway) with SIP dial-peers towards the CUBE and the SRST call-manager-fallback for skinny phones.
I wasn't onsite and only had a short test window (someone else travelled briefly to the site to test). Certainly outbound calls were working and inbound calls are matching the appropriate dial-peers and generating ringback. I can't be completely sure, but I will post again on this thread if I get the opportunity to test.