Ignoring someone that is trying to contact you is rude.
Oscar is working when he gets a text from Mike, an old friend, asking him to talk on the phone.
Oscar wants to keep working.
Oscar sends Mike a quick text, saying that he's busy and to call at a set time that night.
Oscar doesn't answer the text and keeps working on his project.
Oscar and Mike connect at the scheduled time and have a good conversation.
Oscar forgets about the text and never contacts Mike, who thinks Oscar no longer cares about him.