Hi rhweb,
If you use the myroundcube plugins calendar and a caldav backend being SabreDAV plugin or owncloud as I use you can set the calendar plugin to use this as the backend rather than the local rc database.
You then use, which ever tool you want on your phone to connect to the CalDav backend that you are using. For the Apple stuff you can just add the Caldav calendars direct in to the calendar on your iPhone / iPad, I do this for my wife.
For your Andriod phone I just use CalDav-Sync for the calendar.
It's pretty simple.
You can also set up your contacts using CardDAV as well, but that is another story.