There are some instances in which a credit card cannot be run through the integrated credit card terminal assigned to a register.
There are also cases in which a clerk may run a transaction through the standalone terminal due to an internet outage, but is unable to finish the transaction because FieldStack has come back online.
To complete these transactions:
A new button appears on the credit card payment dialog, [Process Offline]:
Pressing this button brings up a similar dialog when FieldStack is currently offline, explaining what is required of the clerk:
After getting an approval from the standalone terminal, press OK and the transaction will complete as normal.