With IP Office Release 11, Avaya Introduced Equinox as the UC/Soft-phone App. differing from other UC clients for IPO office, Equinox gets its IM/Presence components from the cloud. More specifically, the Zang Cloud, or Zang Spaces (http://zang.io/products/spaces). With Spaces you can sign up for a free account, and have some feature rich collaboration similar to the likes of Slack or Microsoft Teams.
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As you can see in the diagram below, the Equinox client connects to the Cloud for IM/Presence needs, while connecting to the local IP Office (premise or hosted) for its telephony features.