My phone does not send or receive any text messages...HELP NEEDED!?

Alrighty. So I have a plan with three people and all of our phones can not send out or receive any text messages. What is wrong with our phones? We have recently paid the bill thinking that was it; but unfortunately our phones are still not working properly. We can make and receive phone calls...and all that other good stuff. Just our text messages are not cooperating...Does anyone know the solution to this predicament?