Cisco TelePresence CE Software Release Notes (CE8)
What’s the difference between a multiway conference and an ad hoc conference?
It’s the call control device. With a multiway conference, we’re using VCS. With an ad hoc conference, it’s Cisco Unified Communications Manager that’s being used as the call control device.
When using a VCS, from the telepresence endpoint s’perspective such as SX series running the CE TC software, you need to select the Multiway option as a Multipoint Mode in the GUI of the endpoint, and the conference is triggered with a “merge” soft button on the display connected to the SX series.
But this configuration is valid before the CE 8.0.0 Software version.
In Cisco TelePresence SX, MX and DX Series Collaboration Endpoint Software 8 Multiway is replaced by ad-hoc conferencing (requires CUCM MediaResourceGroupList).
Adding participants with MRGL Valid:
From CE8.0.0 through CE8.2.1: If you are already connected to an MCU it is not possible to add/merge an incoming call. The “Add” button is replaced with “Answer & Hold” in the incoming call dialog. When you dial into an MCU hosted conference the opportunity to add additional participants was removed to avoid cascaded conferences as this may break content share functionality between the cascaded conferences.
From CE8.2.2: The above change has been modified and the “add” button is available. Keep in mind that if you “add” a participant while already in an MCU call, a cascaded conference may be created (connecting two conferences on two different MCUs hosted at different locations) and content sharing between the two conferences may not work as expected in this scenario. The merge button has been modified and the “add” button is available.
CUCMMediaResourceGroupList means that a Multiparty conferences (ad hoc conferences) are hosted by the CUCM configured conference bridge. This setting is provisioned by CUCM in a CUCM environment and should never be set manually by the user.
Why these changes?
The VCS call control is end of life, and all video endpoints are now supported by CUCM, and since the Multiway is an option in VCS, not on CUCM, a new feature to replace the Multiway feature is needed, this is why Cisco replaced the multiway option by CUCM MediaResourceGroupList option and decided to do this change in the TC software CE 8.X.
Demystify and Simplify 