...
The following values must be unset:
DE Callback
PIN
If the message “Please enter PIN” is displayed on the phone, the PIN is entered in ACE-Client > Terminal UI.
Click on the buttons with numbers until there are at least 4 '*' displayed on the phone then click on "Enter" button.
You may have to click several times on the buttons with numbers and/or the 'Enter" button before the phone takes it into account.
see C-4/American Express TA Session for specific tests
...