Panasonic Toughbook CF-19KHRAG2M Reference Manual page 52

Modem
52
NOTE
This function does not work when the computer is off or is in hibernation.
Connect the AC adaptor.
The screen remains dark after the computer resumes from sleep. The previous screen display will be restored when
you touch the keyboard, touch pad, touchscreen (only for model with touchscreen) or tablet buttons. Do not touch the
digitizer (only for model with digitizer).
The computer cannot resume if the telephone is not connected to the internal modem. (e.g., you cannot use a PC
Card modem.)
The computer needs some time to respond, so set the calling time longer than normal. If this is not possible on the
transmission side, reduce the number of rings before answering on the software that you are using to keep the com-
puter in idle waiting for the call.