RTCP sender reports - when to use?

Hi,

Could somebody clarify a few things for me...

Say, there's a call between A and B in H.323. RTP sessions for both stream directions are totally independent of each other, right? (except with T.120 channel a bidirectional one can be used).

Let's concentrate on RTP session where stream goes from A to B. This one RTP session is a unidirectional channel. Is the related RTCP channel also a unidirectional channel, but to opposite direction? So, if this is true, how can we use sender reports (SR) in H.323? Am I right when I assume that only way sender reports can be used in H.323 is with a T.120 bidirectional channel (when RTCP channel would probably be bidirectional also)?

Cheers, Henri