Glad you asked @OldSchool! You are more than welcome to self-monitor your Alarm system, however, the Professional Monitoring is what features phone calls for Alarm events and dispatch.
While you would not receive a call for an Alarm event while self-monitoring, your phone will be alerted via that app, as well as any shared users. You can also setup email alerts for certain Alarm and Alarm device events. Check out our help center article about Alarm monitoring to learn more! 