Google's surprise announcement on March 13 that it is shutting down support for the CalDAV application programming interface (API) seemingly isn't going to set back Microsoft's plans to incorporate support for Google's calendar syncing protocol.

At the end of January 2013, Microsoft and Google came to a last-minute agreement to extend Google's support of Google Sync, which is built on Microsoft's Exchange ActiveSync, until July 31 -- instead of terminating it by the end of January, 2013, as previously announced. In the interim, Microsoft would build support into the Windows Phone operating system for CalDAV and CardDAV, the Google calendar and contacts sync protocols, the companies announced.

Yesterday, however, Google announced CalDAV API support was being discontinued on September 16, 2013, with the Google Calendar API becoming the CalDAV replacement. However, according to Google's blog post on the topic, some unnamed "whitelisted" developers would be able to continue to use CalDAV.

Google's CalDAV page already lists the API as being "deprecated." A note on the page adds "If you think you have a compelling use case and would like to be whitelisted for the new version of CalDAV API, please fill out this form."

I asked Microsoft officials if the Windows Phone team was among the whitelisted developers. No word back so far.

Google, however, confirmed this will not impact the agreement with Microsoft and that the Softies will still be able to implement CalDav support on Windows Phone.

The Windows team is not going to be adding CardDAV or CalDAV support for users who are trying to connect to a Google account via Mail/Calendar/People after January 30. Here's Microsoft's guidance as to how these users can sync their Google accounts with Windows 8 and Windows RT.

Microsoft officials haven't said how the company will update the Windows Phone 7.x or 8 operating systems to include support for CalDAV. Microsoft is believed to be working on a new minor update to its Windows Phone 8 operating system, known internally as GDR2 -- which may be ready this summer -- which could possibly include the support.