This is important in any business but it might be more important when you are in human relations. By screening your calls you are making good use of your time by not talking to people you don't want to talk to when you don't have time to talk. Get a good administrative assistant who is trained in call screening. If you don't have an administrative assistant you will have to use a device to screen your calls. Do make sure everybody that contacts you gets a response. Don't feel like every response needs to be a phone call from you. You might delegate the responses to staff or even handle them through email, voicemail, or snailmail.