Steps:
Press and hold the iPhone’s physical “Home” button to open Siri.
You will hear two quick beeps to tell you that Siri has woken up and is waiting to do your bidding.
Once Siri has opened, ask a question or ask Siri to perform a task such as calling or texting. Siri will automatically detect when you have stopped speaking or you can optionally press the microphone icon to show you have finished speaking.
Siri will show you a draft of the proposed message before it is sent. To send the message, say “send” or touch the “send” button.