I've spent weeks trying to set somthing like that up for my company, but with no luck. If you have different platforms it's a pain to setup.
In theory you can register a domain name and instal CalDAV php app on it which is supported by majority of platforms. One of those apps would be OwnCloud, which also has some other goodies that come along with it.
However, you will have to test your Android devices with it, as support will vary depending on make, model, and even OS version. There are apps on play store that help you sync CalDAV but as I said it may or may not work.
iOS/OSX always worked for me.
For Outlook you would need to install CalDAV extensions, as it doesn't work out of the box.
As an alternative you could access it using a web browser on unsupported devices, but then there is no notifications, and interface might be hard to use.
After weeks of trying I've decided to setup joint exchange account on every device plus personal and business accounts as needed. Exchange works on every device I tested, being an enterprise solution and you can probably get one for 10$ per year.