I registered my own app as Outlook IM provider, the presence works well but audio/video/IM chat features are grey-out

[zhezhang91]

I checked that Outlook should make several calls to IContact.CanStart to establish the capabilities of the local user, passing in the values for ModalityTypes.ucModalityInstantMessage and ModalityTypes.ucModalityAudioVideo successively to Retrieving the capabilities of the local user (https://learn.microsoft.com/en-us/office/client-developer/shared/integrating-im-applications-with-office)

I have well-defined the CanStart method, but Outlook never calls it.

Any idea how to resolve it? Thanks in advance!