Did you ever previously have Apple? Ask her what color the bubble on her outgoing message to you is. If it is blue then her phone is trying to send you an iMessage. She should try to send it as a text message instead. If you ever had an Apple device that you number was attached to for messaging this could be the cause of this problem.
JENBOY15 Being able to send and receive text messages is important. I'm sorry you've been having problems with your text messages feature. I want to make sure we get this issue resolved for you. Can you please tell me when did this begin? Did you make any changes around that time? What's the make a model of your phone? Please share details. We'd like to investigate for you. EvelynR_VZW Follow us on Twitter @VZWSupport if my response answered your question please click the "Correct Answer" button under my response. This ensures others can benefit from our conversation. Thanks in advance for your help with this.