It depends what kind of background check and company, but generally yes. For high level background checks such as those for top secret security clearances in the military, instead of calling your references and previous employers will actually be visited by a federal agent for a personal interview so that they can get an official signed copy of a statement. For most "background" checks, companies will basically download any police reports that you have associated with you, and then if they feel the need they will call references as they are required by local procedures. Most persons that deal with any sort of information security are very hesitant to provide any information without confirmation of who they are talking to weather it be official documentation or identification, however for a job related call, often the information asked is limited to job performance and not sensitive in regards to personal life. Some background checks require not only provided references, but also use "generated" references, which you will have no prior knowledge that they will be contacted.