Not receiving certain texts from an iphone user?

I have an LG G2, got it about a month ago. Everything was going fine until recently, when I started not receiving certain text messages from an iphone user. It's only some of them, that either aren't been sent to him, or aren't being sent to me. This is a completely new number than my old one, so I haven't switched from any other device. This problem is not happening with anyone else. The iphone user is on AT&T, and I'm on verizon. Neither of us have any sort of problems with other contacts. What can I do to fix this?

You can't fix it if you don't have an Apple ID. The other person will have to. It's iMessage settings for that user. Their contact number listing for you might 'think' you are an iPhone so it's trying to send you an iMessage instead of SMS.
Best luck.