There are several ways you can add someone to your Redlist.
First, when you onboard an imp account, it will import all your contacts. Select “Greenlist automatically” to have all your known contacts automatically added to your Greenlist. Tapping “Greylist Automatically” will import all your contacts to the Greylist. Once onboarded, you can go to the “Lists” tab, and select a list. Tap a contact to change their list assignment to the Redlist.
Once setup is complete, any time you get an unknown call, you can view the call information from the home page (that’s the button with the imp on it in the app at the center bottom of the page).
Tap on the call log notification in the app and you can change the list assignment to the Redlist.
Lastly, adding a contact to your cell phone contact list will automatically update the imp box as well. It can take a few minutes for the imp to fully sync. Once the contact is imported, you can find it in Lists>All Lists and then tap to add it to the Redlist.
Once a number is Redlisted, they can not make your phone ring, and they can not leave a message. The imp just silently handles the call and rejects the caller.