Voicemail: Is this a feature or a bug?

[The Shape]

Somebody called me last night and left a message. It was from a person/number that I didn't know...infact, it was from another state. The person left a voicemail that was probably 45 seconds long. At the end of the message, I pressed 1 to listen to it again because they left some other number to call them back at. I was going to call that number to tell them they had the wrong person and to please stop calling. So I press 1 and it repeated only the part of the message where the guy left his number. I thought that was cool because I didn't want to listen to the whole thing again just to get his number. Is that some feature that can recognize numbers or do you think it was a bug?

 

[plummy]

I think you can skip backwards x-seconds and that might be the button to do so. Might have just been a coincidence that that time interval was when he left the number.

 

[vbnyc]

If you press 5 it will give you the caller id info.