The Verifone Omni 3740 and 3750 credit card terminals are compatible with an Ethernet processing module, which will enable them to process over an IP based connection. The Ethernet module is available in an Ethernet only, and a dual comm version, which includes a phone connection and the Ethernet connection. I highly recommend the dual comm version of the module over the Ethernet only module.

The Ethernet processing module is a small electronic adapter that replaces the land-line module that comes standard with Omni credit card machines.

This is a simple instruction on how to convert your Omni to the Ethernet compatible version.

What you will need:
Compatible IP enabled processing service
Small Philip's Screw Driver
Omni 3740 or 3750
Omni Ethernet or Dual Comm Module
An IP based connection for processing (broadband internet, VOIP, LAN, etc.)

First make sure the terminal is completely unplugged, and make sure you do not have any transactions on the terminal. If you have transactions that are not batched sitting on your terminal, you will probably lose them. Make sure you are batched out.

1. The processing module in your machine is located on the bottom rear of the terminal. It is held in place by a single screw which can be removed by a small Philip's screwdriver.
   
2. Once the screw is removed, the module can be slid backwards and removed from the terminal. Be careful not to touch the medal contacts, as this may damage the module.
   
3. Once the old module is removed, the new Ethernet or dual comm module can be inserted into the terminal, exactly as the old module was removed. Carefully push the new module into the terminal. Again, make sure you do not touch the metal contacts to avoid damaging the module.
4. Once the new module is fully inserted into the terminal, replace the screw that was removed in step 1.
5. Your terminal will now need to be re-programmed in order to operate. You will need to call your provider and they can normally do this over the phone. Hopefully everything will work smoothly the first time and you should now be able to process over an IP based connection.
   

Disclaimer: This guide was written as I swapped out a module in an Omni 3750, so it is accurate to the best of my writing ability. Regardless of that fact, this guide is meant as a reference only. I make no guarantee of the accuracy of this guide, and I am not responsible in any way for anyone messing up their terminal as a result of following this. Credit card terminals are complex and expensive equipment, so if you are unsure of your own ability to perform the swap, I suggest you get help from a qualified individual or your processing company.