No, Karoo is a stand-alone device that houses all of your tools in one good place. On your Karoo, you can customize all of your settings, profiles, and ride plans. Sync your routes, activities, training programs, and group ride information with your home Wi-Fi.
You can even plan routes or make ride adjustments while offline and on the road with sophisticated map layer synchronization.
When you are in-ride, you will be able to get alerts on your Karoo 2 from your iPhone or Android Smartphone. On Karoo 2, you cannot answer SMS or take calls since this is merely a display notice.
iPhone notifications
Android Smartphone Notifications