(Win98, WinME and Win2000)
If you have two phone lines in your home and want to use them both to dial out,
you can use MultiLink, which will effectively double your connection speed.

Create a dial-up connection like your normally would.
Right click on the icon and select Properties
Click on the Multilink tab
Click on Use additional devices
Click on the Add
Click on the other modem you would like to use
If your ISP allows, you can use the same phone number, otherwise enter an additional phone number to dial.
You should now connect with both modems.
You can confirm this by opening up your dial up connection in the System Tray after you connect.