It is really tough to get these "Unknown" callers to realize how they are hurting their cause for getting things done.  Legit businesses will go ahead and have their real name come up and not be blocked.  They have a much better chance of getting the results they want if they would just quit trying to hide behind UKN.  Too much of the tech today simply dumps such calls so they don't get bothered by their BS.  Be honest about who you are, and what you are calling for and maybe people will talk with you to get problems resolved.