Why Do I See Caller ID Photo from Stranger?

Something happened this week that I cannot find an answer to explain online. I hope you can help.

On Monday my cell rings and there on the screen is a full screen picture of some guy pulling up his shirt while looking at the mirror. Seeing the name, I'm like, I don't know who that is, so I don't switch from my call to answer it.

Dude calls back. I'm like who the **** is this guy trying to reach? But I don't answer again. I'm still on another call.

Finally he calls back again after I hang up from my business call. This time, I answer. "Yes, how can I help you?" (tacky man showing your abdomen...) He's like, we are here with your IKEA delivery.

So I was a bit taken aback, of course. It seems that they have the guys use their own cell phones to call about deliveries. But the part that confused me the most is why I got that full screen caller ID picture in the first place? He is not my contact, Facebook friend or anything. He is a complete stranger. So why did I get a caller ID photo from him at all?

When I mentioned to him that I was taken aback by the caller ID picture, he was totally embarrassed and didn't seem to know that the picture was being sent with his calls. He said it was an old picture that he hadn't seen in years.

Thus I don't understand how strangers can have you receive a full screen caller ID photo when you've never met them before in your life. I then reviewed my call log and noticed that the locksmith who came on the same day also had a contact photo displayed, but it was small. I'm not understanding why I am getting caller ID and contact photos at all when I don't know these people.