6. "Hi, this is [your name]. I'm either on a call or away from my desk. Please leave your name, number, and a brief message and I'll get back to you. Thank you.
Consider for a moment how your phone is currently being answered. Professional courtesy is quite often not the standard for many college students. An abrupt "Yeah!" could be listed among the more courteous greetings. The more outrageous remarks will often buy you a major black mark in the professionalism category—even if it was your roommate answering your phone and acting crazy. A simple "This is ____" is always a pleasant change for a college student call. Make the change today, before the next (or first) employer phone call. If you have a landline, you should also encourage your roommate to do the same.

A word of warning: These greetings will not do you any favors if you're in the midst of a job hunt or work in a conservative industry. Always remember your target personas. If there's a chance they won't appreciate your sense of humor, opt for a straightforward greeting instead.
Skype for business also includes not only the physical phone but a suite of features that includes Instant Messaging, Conferencing, Presence and much more. This guide will cover installing and signing-in to Skype for Business on your Windows, Mac OSX, Apple/Android mobile devices. For ChromeOS, please see this link Skype on ChromeOS.