Kolab

The Kolab.org Community is a Free Software initiative building a unified communication and collaboration system that you can install on your own server.

Its aim is to enable contact and calendar synchronization via an IMAP server.

Sync Kolab is an addon/extension for Thunderbird.

Kolab Android is a project to allow synchronization of those contacts from an IMAP server to an Android device.

Sync Kolab documentation page.