What happeneds when you call someone who doesn't have service?

What happens when I call a friend who didn't pay there bill and got their service shut off on an iPhone? If they have Wi-Fi will the call still go through or text?

Nope only text if you also have a iPhone. Like the Imessage.

You'll likely get a message saying their number is out of service. If they have Wi-Fi, that makes no difference- the number you dial won't reach them. They should get a free number thru google or something.