General info ( 25 ) :

• General information links

• 2w-4w Converter - The most surprising thing about a 2w/4w converter circuit is how common they actually are. This kind of circuits are used in telephone system and intercom systems. Converters come in many levels of complexity. Some have a simple level control with no consideration for phase. Others will provide adjustments for phase correction as well as level.   
• An Introduction to Load Coils and Bridge Taps   
• Coherent Communications Articles - full duplex and echo control information   
• Counterintelligence and Counterterrorism WWW Page - information about surveillance and countersurveillance   
• Echo Cancellation Tutorial   
• FCC Part 68 - Connection of terminal equipment to the telephone network - USA regulations on telephone devices   
• How Cordless Telephones Work   
• How Telephones Work - Although most of us take it completely for granted, the telephone you have in your house is one of the most amazing devices ever created. This article is a good introduction to telephone technology.   
• How Telephones Work: The Telephone - Surprisingly, a telephone is one of the simplest devices you have in your house. It is so simple because the telephone connection to your house has not changed in nearly a century. If you have an antique phone from the 1920s, you could connect it to the wall jack in your house and it would work fine!   
• How Wiretapping Works - If people did want to eavesdrop, they could tap into almost any phone line quite easily. This edition of HowStuffWorks explores the practice of wiretapping to see just how simple it is.   
• International Dialling Codes - country codes and dialling prefixes   
• Jeff's Introduction to Load Coils and Bridge Taps   
• Load Coils - Standard voice phone calls degrade noticeably when the copper portion of a phone line is longer than 18Kft (6 km) long. In order to restore call quality, load coils are inserted at specific intervals along the loop. Load coils boost the strength of the voice frequency range (300 - 4000Hz) at the expense of high frequencies.   
• Load Coils - This is a good introductory material on load coils.   
• Nonvoice Calls and Line Testing Tutorial - This tutorial examines the history of line testing and the various challenges brought about by recent technological change, all within a service provider's business context   
• Phone Line Basics - Revisited   
• Phone Lines Demystified From the Engineering staff at Telecom Audio - Phone lines come in many configurations, but they can be summed up as either PBX lines or "outside" lines.   
• Telecommunication Tidbits - links and information articles   
• Phone Line Basics - Reprint from an article printed in June 1996, Radio Guide Magazine   
• Telephone Plug Types by Country   
• Telephony Billing Tutorial - In telephony, billing involves gathering data for customer use and the provision of features, calculating costs, and invoicing for payment   
• Tips for Correcting Bad Phone Lines   
• Transmission lines: Why 600 Ohms? - There are broad definitions, under which every cable becomes a transmission line. Most engineers would narrow the definition considerably. This article introduces you to transmission lines and by 600 ohms impedance has become commonly used.   
• Wireless Local Loop (WLL) Tutorial - This technique to replace telephone wire using radio. WLL can offer the developing world the advantages of a PSTN network, where it would normally be too costly to install a fixed-wire infrastructure. WLL proposes to replace the fixed-line element of a standard PSTN inrastructure with a wireless link. Thus, only the final mile would be a fixed link from a radio transceiver to the user terminal.   
• World Wide Phone Guide - What you need to hook up your modem just about anywhere!   

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