The video below, posted to YouTube by Dany Lisianski, shows a method of accessing contacts, photos, send message, and send email by making a FaceTime call.
*Note: Disabling Siri on the launch screen will prevent this.
Steps to reproduce:
1. Make a phone call (with Siri / Voice Control).
2. Click the FaceTime button.
3. When the FaceTime App appears, click the Sleep button.
4. Unlock the iPhone.
5. Answer and End the FaceTime call at the other end.
6. Wait a few seconds.
7. Done. You are now in the phone app.
Take a look at the demonstration below...