It is probably a Collection Agency. That's why they rarely leave any message, and when they do, they give you a Reference Number.

Keeps calling doesn't say any thing

will call twice a day ,say nothing. THe third call leaves a robo message with a different number to call back. The robo message tries to mkae it seem like I have some sort of business with them by leaving a ID reference number

Somebody keeps calling from this number at all times of the day and when you answer it, nothing happens.  Area 423 is a Tennessee area code.

This number keeps calling me like 4-5 times a day! How irritating!

Who is this?

the number in question belongs to citi cards on behalf of the home depot account consumer credit card. i called the number and this is how i found out.

called...did not leave a message