`Hey Google` hotword now works for some on phones too [Update]
(Android Police)

Update 1: 2017/10/20 1:16pm PDT Apparently, Assistant will prompt you to re-train itself for both `Hey Google` and `OK Google` variations (thanks, Logan): You know how you can say both `OK Google` and `Hey Google` to Google Home and it will respond to the two hotwords without any discrimination? The same isn`t true of Assistant on your Android phone: it only answers to `OK Google.` Wait, scratch that, it wasn`t true as the command is now working on phones too. Read More`Hey Google` hotword now works for some on phones too [Update] was written by the awesome team at Android Police.