Not receiving texts from Greece on Samsung, but just fine on Apple.
So it's all in the family; we all have phones from AT&T - my wife and daughter have iPhone XR, my son and I have Samsung S20.
My daughter moved to Greece; we unlocked her phone and got a SIM from a company there for the few months she'll be there. Her phone is working just fine, it seems; when she sends a text to my wife (iPhone), my wife receives it just fine. When she sends a text to me or my son (S20), we do NOT get it. She does receive our texts, but when she responds we get nothing.
Yes, we've resorted to WhatsApp, but that's a pretty poor answer, no reason text messaging shouldn't work. For the record, I do receive international text messages from other people without any problems.