Voice Control lets you make phone calls and FaceTime calls, and control music playback, if you have Siri turned off. You may want to use Voice Control if you can’t use Siri because you’re not connected to the Internet.
Note: Voice Control and Voice Control settings aren’t available when Siri is turned on.
Use Voice Control. Turn Siri off in Settings > General > Siri, then press and hold the Home button until the Voice Control screen appears and you hear a beep, or press and hold the center button on your headset.
For best results:
Speak clearly and naturally.
Say only Voice Control commands, names, and numbers. Pause slightly between commands.
Use full names.
Change the language for Voice Control. By default, Voice Control expects you to speak voice commands in the language that’s set for iPhone (in Settings > General > Language & Region). To use Voice Control in another language or dialect, go to Settings > General > International > Voice Control.
Voice Control for the Music app is always on, but you can keep Voice Control from dialing when iPhone is locked. Go to Settings > Touch ID & Passcode (iPhone 5s and later) or Settings > Passcode (other models), then turn off Voice Dial.