If you have underground phone wiring in your neighborhood , as opposed to phone wiring that move in the aura on poles , then you will frequently see these little boxes all over your locality – one for every two or three houses or so . A distinctive corner in the southeastern United States might look like this :
This box is two or three metrical unit ( about a meter ) high and perhaps 8 inch ( 20 cm ) square .
If you have read the HSW article entitledHow Telephones Work , then you know that what runs into your house for each telephone line is a pair of atomic number 29 wires . What is running through your neighborhood is a thick underground cable check perhaps 25 or 50 brace of copper wires . The little green box is a place where the 50 - pair cable pop out of the ground so that a earphone company employee can splice into it . They pass off to be build a unexampled subdivision nearby , and here is what one of the boxes appear like during construction :
you may see that this is a very simple installation . They ’ve taken the cable , removed its outer protective sheathing to unveil all of the wire , and then splice into several of the pairs for the two or three houses sharing the box ( the small clean plastic block are the splices ) . Small two - pair cables run underground from the corner to the sign . Sometimes the splices wo n’t be quite this bare – there will be a plastic or ceramic plate inwardly with a articulation block or else of lineal splices .
So where does the 25 - pair or 50 - pair overseas telegram amount from ? If you hunt around your neighborhood , you will find a larger box that looks like this :
This box is perhaps 4 metrical foot or 5 understructure eminent ( 1.5 meters ) . A tumid cable with 100 of conducting wire brace runs past this point , and one or more 25 - pair or 50 - pair wires gets its start here . Inside the loge is a large punch - down panel where phone troupe employees seize each duet in the smaller line to the correct pairs in the magnanimous cable .
The declamatory cable will often get its start at a box like this :
This box is about 6 foot ( 2 meters ) high-pitched and 12 feet ( 4 meters ) wide . you’re able to see on the right hand that this corner also has its own power measure , and therefore has power ( unlike the late boxes , which have contained nothing but passive splices ) . Inside this large powered box are digitizers . The pairs from each house attach to the analog-digital converter so that all of thephonecalls in the area can be carry on a much humble set of wires . This box might accept a number of larger line ( like T1 or T3 lines ) impart voice channel , and the digitizers give down the multiplexed line into single couple . The multiplexed line might travel down the route as cop , vulcanized fiber optic or coaxial cables .
finally the multiplexed lines arrive at aswitchwhich might look like this :
This building has no windowpane and is perhaps 50 metrical foot ( 15 meters ) square . SeeQuestion 354for contingent on what happens at the switch !
