Sending text is successful but receiving is not

[sad cricket]

My wife just got a new S4 and she is using the Chomp SMS text app. She can text her friend fine but her friend will text back but my wife is not able to receive text in response for some reason. It is only this one friend where my wife can't get a reply text. I even tried the messaging app. that comes with the S4 too and the same thing happens. Then I had her friend text me and I was able to text her back without any problems. Does anyone know what is going on?

 

[JudH]

Did your wife have an iPhone before? If so could be imessage related.