Question

Which Service User property is taking into consideration by Office 365 Endpoint when it sets the PreferredLanguage value on the Microsoft Portal side?

This property is responsible for User Interface language in Microsoft Cloud.

Answer

The locale property of http://aps-standard.org/types/core/contact/ APS resource type is using.

It is set in Customer CP > Users (tab) > [Service User] > Language (tab).

Internal content