Is the most effective way to do employment verification for the purpose of providing hobbying services and also the most private.  Typically, companies have greetings which clearly state the company's name and location when the main line (exchange)is dialed, the person calling the exchange then has the option of dialing the extension of the person who they seek to reach.
  It is foolish and unnecessary for a provider to call a person in HR to verify the employment of a potential client.  I think that providers should verify a potential client's place of employment to confirm some key aspects of information that the provider has been given, but if a provider ever asks for the number to my HR department, I would end the conversation and never call her again.