You can select to use Notification Center and/or Pushover (for iOS) notifications under the Caller ID tab.
To use Pushover, you will need to get the Pushover client from the App Store. There is a one time $5 registration fee after a free 7-day trial to use Pushover on as many iOS devices as you like. There is a desktop service available as well.
Pushover notifications may include a telephone number which is a link to dial the corresponding number.