I have the iPhone 7 and it doesn't let me send or receive texts if I'm not connected to the internet or have 3G/4g on? - 1

How do I stop it? I don't have internet so I'm unable to send and receive texts.

The only way to get texts is by using data. You can get around that if you have Wi-Fi but if you don't have access to internet, then you need to turn on your cell phone data in order for the text messages (i.e. Data) to be sent through your cell phone carrier's network.

Turn on your data by doing the following:
Settings > Cellular > Cellular Data to "on". If this is on, and you are still not getting messages, I would contact Apple Support first, and then your cell phone provider next. Hope this helps.