I was excited when I saw the microphone in Messages thinking it was for voice texting

[Supermallet]

Oh ok, gotcha - so how do I tell Siri to text someone, just hold down the home key?

If the phone isn't plugged in, hold down the home key and wait for Siri to pop up.

At this point you can say "Text [message]" and she will show the message as she heard it and ask if that's what you want to send.

If the phone is plugged in (especially useful in the car), say "Hey Siri send [message]" and she'll send it without you having to physically touch the phone.

 

[MotleyGrrl]

Yeah that's my problem, the Siri dictation mic is horribly placed. It's hard to hit and makes the number pad half the size and much harder to hit. I leave Siri off for that reason.

Oh, duh! LOL. Thanks, I just found it

 

[simon48]

Just recorded and sent a short audio message. I thought I saw the word "keep" but ignored it. Upon returning to iMessage it is no longer there... So, my recipient received it. Guess I need to manually keep them. I can see where this might save space. But you lose record of your conversation

Settings > Messages > (audio messages) Expire.

Edit: My bad, I didn't see that someone already said this.