Switching to VoIP

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Chapter 4: Circuit-Switched Telephony

they tend to emit from the other end without losing any power. Switching the light

source on and off allows you to transmit a digital bit stream over the fiber. Attenua-

tion is still a factor for fiber optics as with copper, but the length limits imposed are

much higher—miles instead of meters.

Fiber itself is rather expensive and more fragile than copper, making it a poor choice

for short-distance connectivity. But there are some local area applications where fiber

beats copper. In areas with very high electrical noise, fiber will work where copper

often fails, because fiber cabling carries optical, not electrical, signals.

Because fiber doesn’t use electricity for signaling, it doesn’t require a physical loop.

This means that it can still operate with one strand of fiber, rather than two, intact,

while a copper segment needs two strands intact in order to function at all.

Radio

Radio waves can be used to carry voice and data, though in modern enterprise net-

works, their use for data is far more common. 802.11b and 802.11g are common

standards for deploying Ethernet wirelessly using radio. They offer short-distance

(typically twenty-five to a few hundred meters, depending on the antenna and base)

connectivity for many client devices using