Refer to the exhibit. Which two strings that could be dialed to start a multipoint conference that is hosted by the multipoint control unit? (Choose two.)

52900121 does not correspond to either the MCU conference ID or the MCU's registered SIP URI as shown in the VCS registration exhibit.

[email protected] is the SIP URI of a standard video endpoint, not the MCU, so dialing it reaches that individual endpoint rather than a multipoint conference.

[email protected] is a registered endpoint on a different VCS server and has no relation to the MCU or its hosted conference.

5919 is the numeric conference ID assigned to the MCU-hosted conference and is routed to the MCU by the VCS dial plan as an E.164 or extension number. Dialing this string initiates the multipoint conference on the MCU.

ex90 is an incomplete URI for a regular endpoint and does not reference the MCU or any conference resource.

[email protected] is the SIP URI under which the MCU is registered on the VCS at osl147.local, allowing any SIP endpoint to address the MCU directly and join or start the hosted multipoint conference.