'Why is my iPhone not sending messages?': How to troubleshoot iPhone messaging issues

• If your iPhone is not sending messages, first make sure your phone has service, as the issue may be with the Wi-Fi or cellular network, not your device itself.
• Check in your iPhone's Settings app that various messaging options are turned on so that your phone can dispatch texts if iMessage fails.
• Turning your iPhone off and back on again can usually refresh the software and restore better signal connections, enabling your messages to send once again.

There are few sadder phrases than those two little red words your iPhone displays when a message fails to send: "Not Delivered." Those words, along with that exclamation point in a circle, mean your charming photo or witty comment didn't go through.

Fortunately, as in life, with the iPhone: the simplest answer is usually the correct one. If your iPhone is not sending messages, first make sure you have a connection to either a Wi-Fi or cellular network, and make sure your phone is not set to Airplane Mode.