Key Functionality, also known as Line Functionality, is a type of phone system setup. Key System Units, abbreviated to KSUs, were digital phone systems in the 80’s to early 2000’s that were designed around having phones ring based on what ‘line’ rang. Each analog or ISDN trunk that came into the system was assigned a line key. This line key was then shared out in a shared line account (SLA) that would ring all the phones in the group when the analog trunk rang.
If you ever said “You have a call on line 3,” at your job, chances are you have an SLA set up at your business. Companies often grow using the Shared Line Accounts and do not wish to give them up when they migrate to IP PBXs. In response to this common complaint, ShoreTel designed and released the ShoreTel 212K. The 212K (short for key) is a 12 line phone purpose built for providing easy access to various “lines” on an IP system.
The ShoreTel 212K is perfect for anyone who needs the functionality of an SLA or the ability to mimic a shared line appearance. Modern PBXs have the ability to simulate SLAs for SIP trunks through the invention of Shared Call Appearances (SCAs). Now your company can set up their phone system to enjoy the benefits of IP phones and of SIP trunking while still using their voice switch as an old KSU.