Switching to VoIP

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

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Some service providers sell a service that they call wireless T1. Don’t

confuse this with actual T1 service from a phone company. Wireless

T1 doesn’t have anything to do with T1, it’s usually no good for VoIP,

and it doesn’t use T1 signaling. In fact, wireless T1 is usually just a

name ISPs give to a radio Ethernet bridge that provides a subscriber’s

data network access at roughly the same speed as a real T1 circuit.

Free-Space Optics

A relatively new development, free-space optical (FSO) uses light beams transmitted

over the open air, like a television remote control, to connect remote locations. Like

radio, FSO requires a line of sight and is subject to the same terrain challenges. Like

microwave radio antenna, FSO transmitters and receivers must be carefully kept in

alignment.

But unlike radio products, FSO links are capable of much higher data throughput

approaching 3 gbps. FSO’s range is limited to about a mile. Where radio is suscepti-

ble to RF interference, FSO is susceptible to light interference—especially from the

sun.

More information about metro area networking is available in “Metro Ethernet,”

available at O’Reilly’s Safari Bookshelf (http://safari.oreilly.com), and in O’Reilly’s

802.11 Wireless Networks: The Definitive Guide.

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