Its a very harassing revenue group collection agency.

calls with no additional if

Called about 6:30 pm. I answered and it was a computer voice: "This call is for (my name), if this is not (my name), please hang up. If this is (my name), please remain on the line. There will now be a 3 second pause... beep...beep...beep. This call is for (my name). If you are (my name), it is advised that you listen to this call where no one else can hear you, as it contains personal information." Then it repeats again from the beginning.

They asked me for my birthdate,and told me i have a bill at my local hospital,I'm not sure what to believe what's your thoughts on it.they called themselves the revenue service

Federal law (FDCPA) requires them to send you a letter (US MAIL ONLY) within 5 days of their first contact that contains their name, physical address, the creditor’s name, and the amount of the alleged debt.  It also must contains “mini-Miranda” telling you that it is an attempt to collect a debt and that all information will be used for those purposes.  The one other important thing that this letter must also have in it is that you have a right to dispute the debt within 30 days of receipt of the letter and if you do so, all collection activity must be stopped until the debt is verified.
Read up on your rights here, get template letters to send and also make a complaint at this government site:  http://www.consumerfinance.gov/
Also file a complaint with your State Attorney General's office.
List of State AG’s offices:  http://consumerfraudreporting.org/stateattorneygenerallist.php