Hi @JohnnyAction thank you for your post!
Yes what @Meowmix stated is 100% correct. You will be able to access any feature that does not use/need a data connection (unless you connect to wifi) Just to add to the above list, you would not be able to send or receive iMessages you would only have access to regular text messaging.
Hope this helps!
That is correct! Forgot to mention that! You won't be able to use iMessage or BBM or any social media app for that matter unless you are connected to WiFi. Regular Text messages & Calls will go through without any issues as they do not use data at all.
I would also make sure to turn OFF data on your iPhone so that way you do not access the internet or any app that uses data without knowing even tho they send u a text message its still a good thing to do!