For ad-hoc video conferencing you would need an MCU, TelePresence Server, or PVDM3 modules configured for video (least recommended option) registered to CUCM.
The Jabber iOS/Android clients support VoIP but not video yet. Also, they presently require a VPN connection such as AnyConnect to work outside the firewall. QoS is also a major consideration for the mobile clients; most of the call path is best effort and call quality cannot be guaranteed.
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