CallTo365 was developed with Microsoft and Audiocodes and enables you to connect Office 365 to your existing telephone systems while retaining all functionality.

Existing phone numbers, routing and call center functionality can be configured in the telephone system and used from within Microsoft Teams.

Employees can make and receive calls over the existing telephone system using Microsoft Teams. On every device, wherever they are.

Link: https://callto365.com/

In addition to the official Atos Unify OpenScape Business MS Teams interworking, see OpenScape_Business#MS_Teams_Interworking Callto365 is an alternative interworking possibility without using an on-premise Microsoft certified SBC for Direct Routing and the required OpenScape Business Networking license.

For a detailed description of the configuration and requirements see the documentation below.