IBM ThinkPad 755CX Manual page 72

Using Power Management
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IBM ThinkPad 755CX User's Guide
When the computer is powered with battery power, it turns
power off to the PC Card, so the duration of suspend mode is
longer. When resuming normal operation, if the PC Card or
computer does not operate, restart the application or computer.
When the computer is using one of the following IBM modem
cards and detects an incoming call while in suspend mode, it
automatically resumes normal operation:
– IBM PCMCIA Data/FAX Modem
– IBM High Speed PCMCIA Data/FAX Modem
While the communication link is active, the computer will not
enter suspend mode.