Em,
Please note that when the telephone rings and you choose to pick it up, it is then your responsibility to say hello. I understand that it's them trying to contact you but still you must say hello. Answering the phone, waiting for them to say hello and then just hanging up is not a valid option. The actual ringing of the phone counts as their first "hello." Please remember this in the future to save yourself further pain in the social realm of the world. Let's admit it, you're already suffering in that area.
Also, it helps if you turn your ringer on. This will limit all of those annoying messages on your phone that you never check anyways.
Sincerely,
Common Sense