Scott Muellers Upgrading and Repairing Laptops, Second Edition

Laptops have a number of communications options. Most of the latest communications options attach either through the laptop's PC Card slot, through the internal mini-PCI slot, or via the external USB port. Some older accessories connect to the serial port. More information on these adapters is available in Chapter 12, "Communications." However, two types of communications adapters deserve coverage as accessories: digital phone system adapters and international phone adapters.

Digital Phone System Adapters

Some digital PBX phone systems send out a ringing current that is so high it can harm the tiny PC Card and internal modems in notebooks . Because digital PBX phone systems are now very common in offices and hotels, this can be a serious problem. Replacing a laptop modem can be expensive and time consuming, especially for the internal variety. Fortunately, low-cost filters are available that will protect notebook modems from these dangerous currents (see Figure 14.12).

The Konexx Mobile Konnector from Konexx (www.konexx.com) protects laptop modems by providing a safe analog connection over any digital PBX or multiline phone system. The device works by connecting to the telephone handset jack on a modular phone.

Another product from Konexx is an example of an accessory that should be standard equipment for any globetrotting laptop user 's luggage. The tiny Konexx ModemMinder weighs just an ounce and costs less than $40, yet it could provide valuable protection for your laptop modem. Strung between your laptop and a phone jack, it immediately cuts off communication if it detects an unsafe PBX system. The ModemMinder also protects your modem from power surges, such as those caused by electrical storms.

International Phone Adapters

Just as globetrotting notebook users may need international power adapters, they may also need telephone-line adapters. These adapters are usually sold in a batch that includes an assortment of adapters capable of handling phone lines in most countries of the world (see Figure 14.13).

Note that in addition to using different phone jacks , some countries use different electrical signals to indicate conditions such as a busy phone line. Most laptop modems sold in the United States may not be aware of these different signals. Indeed, these domestic modems often work quite well in international systems, but your communications software will have a much easier time if you use a modem that can understand these international signals. If you intend to do extensive international travel, be sure to carry along a PC Card modem specially designed for international phone systems. Even if you never travel outside the country and are already quite happy with your laptop's internal modem, this extra modem could serve as a valuable backup resource.