ESI Communications has released several phone systems since first producing telecommunications products. These ESI phone systems can be configured to be either analog based, digital, or even IP. ESI Communications Servers, IVX E-Class, IVX 128, and IVX S-Class port cards are all available for purchase allowing users to expand the capacity of their phone system. T1/PRI modules are available for digital line cards, analog station cards, IP port cards, and digital port cards can be purchased for your ESI phone system. Whether you're working keeping a legacy IVX phone system running or looking to upgrade to a newer Communications Server, Dotcom Computers can help you with whatever you need.