Syncing Symbian to Google: SOLVED

I found out how to get all my calendar entries into Google: Sync the events into a single iCalendar file using OpenSync’s Sunbird calendar plugin and import this into your Google calendar. In Sunbird I exported an empty calendar into a local iCalendar file and used this as a starting point; a plain empty file was not enough.

Unfortunately, there is a known annoying bug preventing entries that are older than one month from getting pushed to your Android smartphone—only noted as a “small” bug by Google, though. You’ll have to re-save those entries in the web calendar to update their modification time and have them synced to your phone. This, however, won’t work by updating their LAST-MODIFIED time stamps in the iCalendar file prior to the import.