Lots More Information

Related HowStuffWorks Articles

• How Telephones Work
• How Cell Phones Work
• How Cordless Telephones Work
• How VoIP Works
• Skype vs. Vonage
• How Wiretapping Works
• How does Caller ID work?
• What do digits in phone numbers mean?
• Why does the phone still work when the electricity goes out?
• What do the yellow and black wires in a home telephone jack do?

More Great Links

• The History of the Telephone
• How to hook up a second phone line

Sources

• Crist, Sean. "Doing your own telephone wiring." (May 28, 2008) http://www.ling.upenn.edu/~kurisuto/phone_wiring.html
• Donovan, Dave. "How to Hook Up a Second Phone Line." Do It Yourself.com. 2007. (May 28, 2008) http://www.doityourself.com/stry/addphoneline
• German, Kent. "Two numbers on the same cell phone." CNET Reviews. Aug. 8, 2006. (May 28, 2008) http://reviews.cnet.com/4520-11282_7-6625917-1.html
• Home Tech Solutions. "How Do I…Connect a Second Phone Line." 2008. (May 28, 2008) http://www.hometech.com/learn/hdi11.html
• McAlevey et al. "Multifunction two line telephone system." United States Patent. May 12, 1986.http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4691345.PN.&OS=PN/4691345&RS=PN/4691345
• Michal, Keith A. "Adding a Second Line to Your Existing Phone Jacks." Phone-Man's Home Wiring Advice Page. 2006. (May 28, 2008)http://www.homephonewiring.com/add-line2.html
• Recht, Thomas Stuart, et al. "Method of and apparatus for controlling operation of a multi-line telephone." Oct. 20, 1995. http://patft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5841851.PN.&OS=PN/5841851&RS=PN/5841851