What happens if you text someone with an iphone that is broken/deactivated?

Does the iphone send you a text, or does it say delivered/not delivered, or just never send?

It doesn't delivers simple as that. Obviously if no carrier is connected but if internet's working and you send a text through whatsapp or kik or skype. It'll be delivered for sure

If it's not on service (Didn't pay the bill) you can set up iMessages in the settings with your Apple ID, and text that way.