Company Sharepoint Calendar; making this available on mobile and outlook online

[Andy_J_R]

Hi,

I am trying to move all of our current company calendars from Gmail (shareable link for each user) into O365. We have 5 different calendars (one for each company that we manage), each with a different pool of users, but some users (head office) need to see all calendars in one place or overlayed. Theres a few thousand annual entries, so admin is a consideration.

Each company has a Sharepoint Site / Group Site / Teams. I am currently taking the line of a Sharepoint Calendar on each company site, as it means we can edit events in list view, but importantly prevent any users from editing or deleting an entry (something which I understand you cannot do in a Group Calendar?!)

My issue is there doesn't seem to be a way of broadcasting that calendar beyond the web part on the Sharepoint site; primarily to user's phones and the outlook web app. The reason I want to do this, is to give all users easy access via the screens they use all day, rather than having to go to the Sharepoint site every time they need to check the calendar, as it's heavily used. It also means the users in head office can overlay all of the calendars in one screen.

I have tried adding the calendar into Outlook web app via the Import Calendar > URL, which says it was successful but doesn't show up any entries.

1. Is Sharepoint the best route for this? Main requirements are
   1. Preventing end-users editing the entries
   2. Ease of admin
2. Can anyone think of a way to broadcast the calendar?
   1. Only 1-way sync is required. Editing will always be done through the Sharepoint Site
   2. URL link to the calendar would be fine

Thanks in advance, and open to all suggestions!

Andy

[#2]

You can make Members of Groups read-only on an Office 365 Group calendar, but it will be all members (last I recall).
You cannot provide Guest access to Office 365 Group calendars.
You cannot use SharePoint Calendars in Outlook mobile, only Outlook desktop.

If I recall, you cannot cross-overlay SharePoint Calendars in SharePoint (and certainly not between tenants), but you should be able to overlay in Outlook desktop.

[#3]

@Trevor Seward Thanks for your response.

I had tried to alter the calendar permissions for O365 Group members previously, but failed and read that this couldn't be done. Do you have any links to guides for this or be able to point me in the right direction? Having all members as read only for the calendars would be fine.

That may well solve my issue for the time being. Admin isn't great (no lists) but the usability and sharing is all there, which is primary issue!

[#4]

If you are using the Group's calendar, you can manage the permissions just fine. To switch it to read-only for members, use the following: 

Set-UnifiedGroup groupname -CalendarMemberReadOnly:$true

Or you can even manage the individual permissions granularly now, via the *-MailboxFolderPermission cmdlets with the -GroupMailbox parameter. Some examples here: https://www.michev.info/Blog/Post/2760/managing-folder-level-permissions-for-office-365-groups

[#5]

Thank you for the details and the link, I will try that approach today.