On each device you want to use iMessage on, tap into the Settings app, then tap on Messages. Scroll down to Send & Receive, and tap through to that screen. You’ll see your Apple ID at the top, and then a section titled, “You can be reached by iMessage at:” with one or more phone numbers or email addresses there.
When you call a dead phone does it ring?
Answer: A: With a dead battery it should not ring but it should go to voicemail directly.