For the ultra-private, we've made it possible for you to add people without actually sharing access to your contact list — just choose the 'add manually' option

For the ultra-private, we've made it possible for you to add people without actually sharing access to your contact list — just choose the 'add manually' option when adding a friend, and enter anything you want for their name/phone number. The app will still work as a single-player option. There's only one feature you'll miss in this case. You just won't be able to share availability with someone unless they log in with the same phone number as what you've got stored in your contacts. This is to ensure that only friends you add are able to see your availability.