Wiring can be extended from jacks or from the junction where wiring enters the home. The rule of thumb is to use the method—or a combination of methods—that results in the shortest run of wire.
Telephone wiring is thin, meaning it is easily routable but also easily damaged. Because of this, do not run wires nor install jacks:
• Near any source of heat, such as water pipes and air ducts, which can corrode the wiring.
• Within several inches of electrical receptacles, which can cause interference on the phone line.
• In the same conduit or to the same junction box as electrical outlet wires because a short could cause a surge of current to the phone wire.
• Close to faucets, sinks, swimming pools, tubs, showers, hot tubs, and any other source of moisture (including damp basements), where the use of a phone could constitute an electrocution hazard.
• Too close to large, grounded appliances in a kitchen.
There are several options for running new wiring when extending a phone system. The simplest is to just leave it exposed, though this is not only unsightly but also leaves the wiring vulnerable to being damaged. Below are some alternatives:
Concealing exposed wiring. To protect the new wiring and make it as unnoticeable as possible, look at nearby cabinets, closets, shelving, door and window frames, baseboards, and other trim. With the use of telephone wire clips or staples, the wire can be secured along any of these features, making it almost invisible. Better yet, if you have carpeting, simply remove the hardware along the edges, route the wire underneath, and then re-tack the carpet
Routing wire through walls. If your home’s walls are made from drywall (as opposed to lath and plaster), it is very easy to drill through a wall to route telephone wires from one room to the next. Find a spot between studs (using an electronic stud finder makes this foolproof) and drill through the wall just above the trim with a 1/4-inch drill bit at least 5 inches long. Inserting the wire into a straw will make feeding the wire through the wall a snap.
Floor-to-floor wiring. While running phone wire between rooms almost always requires cutting a hole in a wall, running a line vertically is actually easier than running it horizontally. You simply route the wire through one wall, down below the subflooring, and then back up into a hole in the adjoining room’s wall.