The app communicates with Dynamics 365 Business Central by using Dynamics Mobile Platform as a proxy service, e.g. Dynamics Mobile Platform forwards requests to Dynamics 365 Business Central by calling the Dynamics 365 Business Central ODATA interface. This requires the Dynamics 365 Business Central instance to have the ODATA interface published to outside for inbound requests. It also must allow outbound requests to be made from the Dynamics Mobile Add-on.