A terminal is getting a 912 (or 902) Decline

This occurs when you have First Data as a processor and you have a terminal that is not used that often and is un-used for multiple months.
The error will have the following message:

Error Performing electronic payments transaction on Credit Card: INV TERM ID-912 DECLINE.

902 might be in place of 912. and "Credit Card" will be where your credit card Payment Method name will be.

First Data will deactivate a terminal that has not been used for a long time.  You will need to contact them to get it turned back on.  If you have a local rep for First Data, that is the best way to handle this.  If they are not able to handle it or you need to contact First Data directly, a tech can help you with the information you need to get the terminal re-activated.