Which ITU-T recommendation defines the procedures for using more than one video channel in
H.320-based systems?

A.
H.324

B.
H.230

C.
H.239

D.
H.264

E.
H.329

Explanation:
H.239is the ITU standard for a second video channel; this is supported by all the
major vendors, and is the only content channel standard supported by Cisco acquired Codian
products or Cisco TelePresence Serial Gateway Series products on H.323 video calls.Cisco
acquired Codian products need to be configured to enable H.239. Any H.323 endpoint that also
supports the H.239 protocol can source this channel, as can a VNC connection, though some
endpoints need to be configured to use H.239 instead of their proprietary solution.