Why can't one person send me text messages but can receive one from me?

[AC Question]

one person cant send me text but can receive one from me

We are on same ATT plan. I can send text and she receives it. She sends me text and I DO NOT receive it. Both of us can send/receive to other people. The only thing that does NOT work is she is unable to receive MY texts to her. And this was never a problem until two days ago.

 

[VW Maverick]

Re: one person cant send me text but can receive one from me

Welcome.
What devices do each of you have?
Are you using the stock Messaging app or a 3rd party app?
Any updates or changes to either plan or device 2 days ago?

Mav.