If your team uses Slack, the popular real-time messaging application, you may consider setting up Teamup-Slack integration, so that everyone can be instantly notified of changes on your Teamup Calendar via Slack channels.
The Slack integration makes it possible for any Teamup users to receive calendar change alerts on desktop or mobile devices via Slack, in addition to getting notifications by email.
We have updated the documenation to make it clearer about the two setup methods, one for group channels and one for private channels. For security reasons, it is recommended that only the calendar administrator should set up integrations for group channels on Slack. If you are a non-administrator user, you may use your own calendar link to set up the integration that will post notifications about your calendar changes to your private channel.
Teamup Calendar can help you organize the signup for an event. Signup is an option that can be activated inside the event editor for each event. If signup is activated, calendar users can sign up for an event with their name and email address. You as the event organizer can easily keep an overview of who have signed up.
Read more at http://calendar.teamup.com/kb/signup-for-an-event/