I don't recognize this as a prefix of the 256 area code, plus it brings a song to mind. The guy said he was Davon with URS, but asked only for me by 1st name. No calls back after I hung up.
In order to stop these types of calls from collection agencies, you will have to write or fax a cease and desist letter to the company. Then by law they are not allowed to contact you at the number they have been harassing you at.
If you do not owe the debt, then please stick up for your rights by contacting a consumer rights lawyer within your state. If you do owe the debt, then a cease and desist letter is good and tell the agency that you will only want to be contacted via mail only. And make sure you pay them if and only if you owe them.