Symptom:
When users are in a conference call in UCM version 9.x, they would always see self video image, and one other user's video image, they can't see the video image from the rest user.

Users should all see each other's video. 

But this issue only happens in UCM version 9.x.

Conditions:
1.user1,user2 and user3 are all signed in phone service under ucm version 9.x
2.establish a conference call among the three users

Result:
each user can only see self video and one other user's video, always missing the video image from the rest user

Expected result:
all users should see each other's video image