Built for diaries other people write into. Open Lines reads free/busy across your Microsoft 365 tenant — including meetings colleagues put in your calendar — and books inside the rules your administrator already set.
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Outlook is rarely one person’s diary. Colleagues send invitations, appointments sit in shared mailboxes, rooms have calendars of their own, and an IT administrator decides what any application may do. Open Lines works inside that: it authorises through your own Microsoft account, reads free/busy rather than copying anything out, and creates an ordinary calendar item your organisation can forward, edit and govern like every other meeting.
Whatever your tenant requires applies — if your organisation asks administrators to approve new applications, yours approves it once.
A meeting a colleague put in your diary makes that hour unavailable exactly as one you created does.
An individual diary, a shared mailbox or a room calendar — wherever your colleagues already look.
Availability is read at the moment of the call. Nothing about your diary is exported or held elsewhere to make booking work.
It syncs to phones, shows in Teams, and can be forwarded or amended by anyone who would normally amend a meeting.
Conditional access, retention and sharing limits continue to apply. Connecting a phone line does not create an exception to them.
Microsoft 365 exposes free/busy across your organisation, so the assistant can see that a slot is genuinely clear before offering it — including time blocked by meetings you were invited to rather than ones you created.
Teams that book into a shared mailbox or a room calendar rather than an individual one keep doing exactly that; the appointment lands where your colleagues already look.
The connection is authorised through your own Microsoft account, so whatever your administrator has set — conditional access, retention, sharing limits — continues to apply. Nothing is copied out of Microsoft 365 to make booking work.
A booked appointment is an ordinary calendar item. It syncs to phones, shows in Teams, and can be forwarded or edited by your team like anything else in the diary.
Yes. You authorise it from your own Microsoft account and it reads the calendar that account can see — whether that is a personal mailbox, a shared one, or a room.
Yes. It reads free/busy, so an invitation you accepted blocks that time just as an appointment you created does.
Yes, if the account you connect has access to it. Teams that already book into a shared mailbox keep doing exactly that.
That depends on your tenant. Some organisations require admin consent for new applications; if yours does, your administrator approves it once.
No. Availability is read at the moment of the call and the booking is written back. The calendar remains the only copy.
From your Open Lines dashboard, or by revoking the application in your Microsoft account. Either stops it immediately.