Architecture

Regarding the architecture of Skype for Business Online, there are three models:

• Cloud only
• Skype for Business on-premises
• Skype for Business hybrid

Cloud only

The cloud-only model is used as Software-as-a-Service (SaaS). Microsoft has your identity and manages the Skype for Business infrastructure. You can also have some add-ons, such as Microsoft's cloud-hosted Private Branch Exchange (PBX) and the Public Switched Telephone Network (PSTN) calling service:

In cloud-only scenarios, organizations use the Skype for Business service only on the Microsoft infrastructure.

You can learn more at https://docs.microsoft.com/en-us/skypeforbusiness/skype-for-business-online.

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