The owncloud server at ICM offers a calendar service. You can create your own calendar(s) and share them with other ICM users.

Adding a shared (eg. team) calendar to your owncloud
1. Within owncloud, this is automatic. If someone shared an owncloud calendar with you (as described below) you have nothing to do to see it in your owncloud calendar.
2. Just log into https://owncloud.icm-institute.org
Adding a shared (e.g. team) calendar to Google/Microsoft calendar
1. On your way to de-googling your life, you're not there yet. You're a victim of the extremely well done Google services, and want to keep working instead of configuring a half baked workaround with Thunderbird or another open-source tool.
2. In your https://owncloud.icm-institute.org/index.php/apps/calendar/, click "partager par lien public" to share your calendar, or any calendar that you have access to and open the link
3. This will open a new tab with a "S'abonner" button in the top right corner.
4. Right click that button and "Copy link"
5. Then paste that link in Google's "import by URL", or Microsoft's similar calendar subscription menu.
6. You will NOT be able to add or modify events from Google or else, in this way.
Creating your own shared calendar
1. Log into https://owncloud.icm-institute.org
2. A page opens with a frame on the left. Click on Calendar, then + New Calendar, name it, click Create.
3. To share the calendar with other users, click the share icon, then enter the names of your coworkers (NB: 20/10/2017, this displays cryptic suggestions. Keep typing the name until there's only one possibility and choose it. This bug has been reported.) Don't forget to tick the "can edit" box so your colleague will be able to add events to the calendar.
4. That's it. Your colleagues should see the new calendar in their own owncloud calendar page.
5. Every one of your colleagues with "can edit" rights will be able to add events to this shared calendar.
Importing a shared owncloud calendar to your favorite client
1. Thunderbird
  1. Install the "lightning" extension: download the plug in and save the file somewhere.
  2. Open it in Thunderbird. Menu on the right > Add-ons, then gear menu > Install Add-on from file...
  3. A new button appears in the top right corner of Thunderbird
  4. Back to the owncloud page where you created the calendar, copy the link in menu "..." next to the calendar then "link". (NOT share public link)
  5. Once you open it, you see a calendar table and a list of your calendars on the left. Right click in it > New calendar... > on the network > CalDav, paste the address you just copied.
  6. Next, choose your ICM address, name the calendar, choose a color and you're done.
  7. This calendar is synchronized between this computer and all of the people it is shared with.
2. Android phone

Using DAVx5 app.

url base : https://owncloud.icm-institute.org/remote.php/dav

utilisateur : prenom.nom

mdp : celui de l'ICM

updating password should be no problem.

~~Follow instructions here: https://aide.lws.fr/base/Autres-services/Messagerie-professionnelle/configurer-calendrier-partage-Android~~
~~Fill user, pass, server as follows:~~
User : nom.prénom
~~Password : *******~~
URL : paste the same link from the owncloud page (see above point 3.c.iv). You may want to email it to yourself and copy-paste it here because it's a rather long url...
~~To this day, it seems like you will have to reconfigure this account every time you change your ICM password. Enjoy!~~

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