• Home

• Preface

• Alexander Graham Bell

• Telecommunications history

• How the telephone works

• Phone FUN facts

• Why the Phone Works When the Lights GO OUT

• FTTP (Fiber to the Prem)

• Future of Telecommunications

• Crossword Puzzle

• Word Search

• Glossary

• Credits

• Speech by Thomas Watson

Why do the Telephones work when the Power is OUT !

Telephones use electricity to make and receive calls. But when the lights go out because the electricity is interrupted…, do the phones still work? If so, why?

The answer is yes they do still work.

Yes, because the telephone company provides the power to operate nearly all home phones. A long time ago they realized how important it was to ALWAYS be able to have the power needed to run everyone’s phones. So throughout the Bell company millions and millions of dollars were invested in something called “power plants” Not plants as in – “garden plants”, but rather rooms of generators and batteries. Development of power plants began as early as 1893.

AC to DC Converting Power Plant

In a telephone exchange, the power plant equipment continuously supplies the electricity in its various forms and voltages to keep the telephone equipment operating. To operate them the phone company purchases commercial power from the local power company.

Nuclear Power Plant