As the central hub of all functions of your ESI business telephone system, the main system cabinet is often referred to in the industry as the KSU - Key Service Unit. While this particular term might not fully explain the robust functionality of modern day systems, it has become the short-hand description for “the box that runs the phones and hangs on the wall.”
While every effort has been made to categorize the ESI phone system KSU’s offered for sale here, you may encounter systems which are cross-branded - meaning the exact same equipment was manufactured under more than one brand name. If you have any difficulty finding what you need or don’t see it listed for sale, please contact us and we will get back to you with any help we can offer.
Please note that in the highly proprietary world of business telephone systems, there may be multiple revision numbers, software releases or other critical differences between seemingly-identical components that may impact the exact equipment you need. Please contact us if you have any questions regarding compatibility, system capacities or any other issue.
We are happy to offer customized ESI packages as inventory allows; if you would like to inquire about building a complete system with phones please send us a message with your specific needs and we will work on a quote for you.