comm

The comm device class consists of communications ports. You access these devices by using the Win32 file and communications functions.

The lineGetID4OL17WJ and phoneGetIDCQL49I functions fill a VARSTRINGFZOPJB structure, setting the dwStringFormat member to the STRINGFORMAT_ASCII value and appending a null-terminated string that specifies the name of the communication port (such as COM1). You use this port name in a call to the CreateFile function to open the communication device for the line or phone.