Brief description of how Alert Central works with Sharepoint calendars

I have read message threads and documentation that mentions the OnCall calendar feature of Alert Central. These sources seem to hint at some ability to connect to a Sharepoint calendar in some way. However, I have yet to find any details as to how this would work.

Does Alert Central actually import calendar data from a Sharepoint server, or does one actually have to manually configure the OnCall feature in Alert Central?

In other words, to what extent, if any, are Alert Central and Sharepoint actually integrated?

This is a critical question in our decision on whether to use Alert Central, since we would like to "automate" the use of the on call calendar we currently maintain in Sharepoint.

Thank you.