King County uses a Unified Communications system (UC) for internal and external communications. It replaced the old telephony system. (yes, that’s a word. “Telephony is the technology associated with the electronic transmission of voice, fax, or other information between distant parties using systems historically associated with the telephone, a handheld device containing both a speaker or transmitter and a receiver.”)
To provide clarity: Skype is the Microsoft consumer version for personal communications you use (for free or a small fee) to communicate with people. “Skype for Business” is Microsoft business version that King County’s uses. It is a more professional and robust version of its personal/consumer little sister. It has instant messaging, screen sharing, conference calls, voicemail, and shows whether someone is free to take calls or messages. Using Skype for Business for instant messaging keeps those quick, check-in emails out of your inbox and provides a free alternative to Webex or GoTo Meeting.
Lync is the old name for Skype for Business that will appear on devices like MAC products until Microsoft releases a Skype for Business client for that OS.