What Are the Differences Between ESI IVX Phone Systems?

Posted by Rick Torres on

ESI IVX 20 Plus Phone System

ESI is an American manufacturer of phone systems, which was founded back in 1987.  Over the past 28 years ESI has released several different models of phone systems.  Many of these systems begin with "ESI IVX", IVX standing for "integrated voice exchange".  This brings us back to the topic of our blog... so what's the differences between all the IVX phone systems?

ESI IVX Classic:

This phone system is not actually called the IVX Classis. Rather, this is the colloquial name given to the system which is simply known as the ESI IVX. The system only works with the EKT-A telephones. The EKT-A is an analog phone that looks a lot like the ESI DP1 phones. You can tell an EKT-A phone apart by looking for the slider directly above the number pad. This phone system is rarely used now, but refurbished EKT-A phones can still be found.

ESI IVX 20, IVX 20 Plus, IVX 128, and IVX 128 Plus:

There are several differences between these individual phone systems; however, this series of phone systems all use the same phone, the digital ESI DP1. The main highlights to know are that the ESI IVX 20 is the smaller system with limited room for expansion. By default, the IVX 20 can support 4 CO trunks and eight digital phone extensions. It can be expanded to support an additional 2 CO lines, four digital ports, and two analog ports.

On the other hand, the ESI IVX 128 is the larger enterprise level phone system. The 128 system can be expanded and accept several different modules, even supporting a T1 module. This system can accept the 684 port card, 612 port card, D12 port card, DLC12 Port card, and the A12 port card.


What does the "Plus" mean?

The plus refers to whether or not a voicemail option has been installed into the system. If your company is looking for internal voicemail, be sure to select an IVX 20 plus or 128 Plus system.

ESI IVX C-Class:

The ESI IVX C-Class is a newer small business phone system. The phone system can use either 12 or 24 button DFP phones. The larger ESI 48 Key DFP phones cannot be used with this system.

ESI IVX S-Class:

The ESI IVX S-class system can use all three of the DFP phones, the 12 key, 24 key, and 48 key. This phone system comes in two different generations. Generation 1 is the 42S system and generation 2 is the 56S system. These systems use different port cards, but both cards are 4x8x2 configurations.

ESI IVX E-Class and X-Class:

The ESI IVX E-Class and X-Class phone systems use the 12 key DFP, 24 key DFP, and 48 key DFP phones. These systems can also support the IPFP 48 Key telephones. These systems also come in generation 1 and 2 configurations. Be sure to select the right port card for your generation.


Here at Refurbished Phone Exchange, we sell a wide range of ESI equipment.  If you have any questions regarding the right ESI phone system for your business, or need help finding the correct phone for your phone system, please don't hesitate to contact us... we'll be happy to help!

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