Cable and DSL modems are almost always part of a desktop installation and
therefore are external devices.
Whatever the design for your modem, the use of a router generally permits
sharing a connection amongst more than one laptop or computer. Sharing a
dial-up modem is likely to be less satisfactory than using the greater speed
and capacity of a broadband device such as a cable or DSL modem.
On a desktop machine, I usually recommend use of an external device for sev-
eral reasons:
They offer LEDs and other indicators that tell you the link status.
They can be turned on or off independently of the computer itself.They can be easily replaced if they fail, a much simpler task than dealing
with an internal part.Laptop users can have it both ways, using a tiny internal modem plugged in
to the PC Card slot, a mini-PCI slot, or a miniature device attached to the USB
port. The least attractive option for laptop users is to work with a full-sized
modem that requires a serial cable.
Troubleshooting an external dial-up telephone modem ...............
An advantage of an external modem is the ability to isolate it from the com-
puter itself for testing. To do so, start by checking the modem itself.
Is it plugged in to a power source and turned on?
The source of power may be an AC adapter or a USB port. When power is
applied, do the modem LEDs or other indicators illuminate? Are any flashing
or otherwise giving you a report on a built-in self-test for the device?
Is the cable from the modem to the laptop
properly connected at both ends?
Older modems typically attach to the serial port on a laptop; newer models
generally use the USB port or install in a PC Card slot. Check for crimps, cuts,
or damage to pins. Make sure the cable is squarely attached so that all pins
make contact.
Don’t assume that a cable will last forever. They can die a thousand deaths:
stretched to the point where wires break or pull out of their internal connec-
tors; broken or thinned by repeated heating and cooling, or burned through
Chapter 15: Modems: The Essential Translators 233