What are Phone Jacks?

Mary McMahon
Mary McMahon

Phone jacks are wall-mounted terminals which are used to connect a telephone to outside wiring, which leads eventually to a central phone system. Much like power outlets, the configuration of phone jacks varies from nation to nation, but it is usually standardized within a country. Many homes have at least one phone jack, with larger homes and businesses usually having multiple phone jacks. Phone jacks are integral to telephone connections, and they are also often used for data connections as well. To connect to a phone jack, a consumer uses telephone cord with a plug which matches the phone jack.

Phone jacks are needed for landline phones.
Phone jacks are needed for landline phones.

When telephones first began to be widely used, they were usually hard wired into the wall by the telephone company. As telecommunications expanded, this became impractical, and telephone companies designed customized jacks for their customers. Eventually, the use of a standardized jack which would allow customers to switch easily became widespread. In the United States, most private homes have an RJ11 type jack, which allows a connection for a single phone line. An RJ14 allows two, and numerous other configurations are available for more lines. All of the RJXX style jacks have six pins, which are utilized differently depending on how many lines are run through the jack.

As a general rule, the phone company is responsible for maintaining outside wiring and connections. The outside wiring leads to a switching box on the exterior of the house, which has lines running inside to the phone jacks. Depending on the region, a landlord is usually responsible for the inside wiring for one jack only. Additional jacks are the responsibility of the tenant. Many phone companies offer service plans which include installation and maintenance of additional interior phone jacks.

When a new home or business is built, the contractor typically installs a multitude of phone jacks, to ensure that the telecommunications needs of the clients will be met. This saves a great deal of time and energy later for all parties, as does installing ample electrical outlets. Installing additional phone jacks in a home is relatively easy, and many consumers are able to do it themselves. When supplemental lines are installed, it may be necessary to upgrade the wiring to the phone jacks of a home, depending on how old they are and how they were installed. Consumers who are not comfortable handling their own telephone wiring can pay an installation service.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a EasyTechJunkie researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


What year were phone jacks available in California?


It's funny how much the world has changed in reference to phones since I was a kid. I remember in the 90s, my sister saved her allowance to pay to have a wall phone jack installed in her room so she could have her very own private telephone. (Not her own line, just her own phone, so she could talk to her friends and have privacy.)

But now, a lot of families don't even have land lines. (We had one in our last place so we could have DSL, but now we do not.) Each member of the family has their own cell phone - no jacks required. Not only can kids talk privately in their room, their friends don't even have to call the main number and "risk" talking to mom, dad, or little siblings.

I think this makes for more need for vigilance on parents' parts. It takes a little more effort now to know who your kids' friends are, but it's important!


For a room that lacks a phone jack, an option can be a phone system in which several handsets need only one jack. Basically, you plug the main unit into the jack and then there are satellite units that only need an electrical outlet.

Our old house had no phone jack in the living room, for some reason, but we really wanted to have a phone in there. So rather than pay for a new phone jack installation, we just got one of these phone systems. I think it could support up to four satellite handsets but we only needed the one. The satellite was a cordless, and the base unit was a corded desk phone with a built-in answering machine.

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