Why did i receive a ∆ failed on a text that sent 5 days ago?

[AC Question]

I sent a text 5 days ago. On the bottom of the text, 5 days ago, it said SENT. Today it says failed. Anybody have an idea of what happened or has had this happen? I honestly don't want to call or text this person again.

 

[B. Diddy]

Welcome to Android Central! Do you know for sure that the recipient didn't actually get the text?