For best results with an external high-speed modem, you also need a high-speed serial port. If you have an internal high-speed modem, it has a high-speed serial port built in already. The early PCs had relatively slow serial ports built around a chip called an 8250 UART. Many PCs today (and most laptops) still ship with these obsolete chips. If you have an external high-speed modem and a PC with slow serial ports, you should strongly consider upgrading your serial ports to the newer high-speed chip called a 16550 UART. If you aren't sure what kind of UART you have, you can find out by running the MSD (Microsoft Diagnostics) program. If you have an 8250 and you experience transmission problems or lost data at high speeds, call your computer vendor and ask about an upgrade to a fast serial port. A fast serial port is even more important when you run other Windows applications simultaneously with PC Access.