Siri does not work on older iOS devices. The iPhone 3GS, iPhone 4, iPad, iPad 2, and the iPod Touch 1st-4th generation do not support Siri. Even though these devices may be able to install a version of iOS that supports Siri, they won't be able to use it.  Visit support.apple.com/en-us/HT201296 for information on identifying your iPhone if you're not sure. See Determine an iPad Model / Version for information on determining what model iPad you have. See Check Your iPod's Generation for information on identifying different iPods. The information in the first section will help you determine what generation iPod Touch you have. You can change your Siri settings from the Settings app on your iOS device. This will display the general settings for your iOS device. If you don't see "Siri" in the list, which should be right towards the top above "Spotlight Search," your device is not compatible with Siri. By default, Siri will be on. Tapping the toggle will switch it off or on. This feature allows you to say "Hey Siri" to activate Siri if your device is plugged into a power source. Siri gets a lot of functionality out of your iOS device's current location. Enabling location services will allow you to do a lot more with Siri. Location services are enabled by default, but you may have disabled them:  Open the Settings app and select "Privacy." Tap the "Location Services" option. Ensure that Location Services is toggled on, and that "Siri & Dictation" is set to "While Using."

How would you rephrase that briefly using Vietnamese?
Đảm bảo rằng thiết bị iOS là tương thích. Mở ứng dụng Settings (Cài đặt). Mở mục "General" (Chung). Chọn "Siri" từ danh sách hiển thị. Nhấn vào nút bên cạnh "Siri" để bật hoặc tắt tính năng. Nhấn vào nút bên cạnh Allow "Hey Siri" để bật/tắt khẩu lệnh "Hey Siri". Đảm bảo rằng dịch vụ định vị đang bật.