The analogue Plain Old Telephone System was designed to transmit human speech frequencies along pairs of copper wires over very long distances. Problems included signal loss (attenuation) which increased with frequency, local noise interference, and a delayed echo from the far end.
Local interference was reduced by twisting the pairs of wires so that the interference was similar for both wires and would be cancelled when connected via a transformer.
Differential higher frequency signal loss could be reduced by correction circuitry.
A special double transformer was designed to separate the incoming and outgoing speech within the telephone, and the microphone was physically separated from the speaker.
The echo effect occurred whenever there was a variation in line quality, so it is important to match the end load to the cable characteristics whenever a telephone is in use, (not important for telephones when they are not in use). Otherwise, anything connected to the cable end should appear identical to an infinite length of the same cable.
DC power was supplied through the wires, and sensing a make/break line connection enabled automatic dialing and routing.
Very low frequencies around 17Hz were used to drive the ringer device, separated by a large capacitor. It was possible to use multiple telephones as long as they were not connected at the same time, and the ringer drive was separated at the line termination box, although this involved a third wire locally, breaking the continuity of the original twisted pair.
Higher frequency data can be transmitted using ADSL broadband up to about 5 Km, or VDSL (FTTC) up to a few hundred metres, despite the severe losses in twisted pair cables. However losses can be far greater if the data frequencies are allowed to escape into local telephone wiring, which will also act as an aerial collecting local interference. This is minimised when the telephone wiring is isolated by a filter mounted directly on to the line termination box, while the original ringer capacitor is unused but replaced by a capacitor following the filter components. The high frequency data is connected direct to the modem, and the modem is designed to match the normal line quality at the used frequencies.
The standard Network Termination Equipment NTE5 box is designed so that all local telephone wiring is connected to a removable lower front panel, allowing easy removal for line testing. An inexpensive faceplate replacement lower front panel is available containing the correct filter components, although there are different versions to match the ADSL or VDSL data system and the physical shape of the NTE5 fitted. A VDSL filter may also be suitable for ADSL. The T70-5977 is listed by millsltd.com as suitable for both VDSL and ADSL with the flat-front NTE5-A at £4.24 + VAT.
If the modem must be located away from the NTE5 it should be connected using twisted pair cable that matches the characteristics of the incoming telephone line, either standard telephone cable or a single pair from ethernet cable.
Some cables are marked Dca or Cca to show that they comply with EU fire safety requirements, but beware that some suppliers list Copper Coated Aluminium (CCA) cable which is cheap, OK for temporary use, but does not meet standards and will quickly corrode and fail.
Openreach "Information for developers" reports that the latest regulations require that ALL cables should be in conduit, so they may refuse to install where they find ANY cables that are not protected.
UK Broadband information, http://www.thinkbroadband.com including a map showing which companies have already installed Fibre To The Home (FTTH), Fibre To The Premises (FTTP) for example shared fibre to a tower block, and other connections.
If and when Fibre To The Premises FTTP becomes available the maximum possible data rate may be much greater than actually provided initially. Local internal connections may be adequate at first, but may need to be upgraded for the future. Up to around 50 metres of Cat5E cable may be adequate for Gigabit ethernet, Openreach suggest Cat6 for some future proofing, but internal fibre networking may soon become the normal, so consider the use of ducting with a minimum number of smooth bends suitable for fibre, and keystone patch panels that can be converted to take fibre. Data distribution equipment is available with optional plug-in adapters, see http://www.millsltd.com.
You can "Register an Interest" in getting FTTP via several websites.
http://www.Openreach.com provide information about their current installation work under Broadband "Fibre First" and "Where and when we're building" including a map with the latest schedule, and much more under "Fibre for developers".
Other independent companies are installing their own networks, and provide details on their own websites, see The Independent Networks Cooperative Association "https://www.inca.coop/membership/current-members"
Fibre connections may run for 50 Km without a repeater, and are cheaper to install than copper, the old copper cables can be recovered for scrap, while fewer telephone exchanges are required. However more connections are now required for an increased number of wireless links to support mobile use.
Dedicated low power line-of-sight radio links using highly directional aerials may be able to work over considerable distances, perhaps 75 Km using 1 metre dish aerials under perfect conditions, but they can be badly affected by weather conditions, trees, including their leaves at specific times of the year, nearby conditions and reflective surfaces including the state of the tide since water is a good reflector, and solar radiation. However do not expect standard WiFi to give reliable results through walls, or where there are multiple reflections, or in the presence of other nearby sources which may not be in the same building. There is a legal limit to the amount of power transmitted, although directional aerials can help, so some modems provide a mini aerial array which can be angled for the best result. A local network may already connect using gigabit ethernet, but expect more problems as network data rates increase in the future.
Openreach suggest installing WiFi at ceiling level in the main room used for computers, so clear of obstructions. Another suggestion for the future is an optical alternative to WiFi using a specially adapted LED lamp, although that may introduce a greater security risk from direct access through the window.
Internet standards provide some fault tolerance by allowing repeat transmission requests at the cost of effective connection rate.
There is no direct connection between the analogue Plain Old Telephone System and the internet, but some internet providers do provide a link which may even use the same old telephone number, although there may be an additional charge for the service. However there are various ways to connect using Voice Over Internet Protocol (VOIP) without any additional charges. The Openreach Optical Network Termination units no longer provide a standard telephone connection, although some modems do provide a suitable replacement, or use a cheap stand-alone converter. There appear to be several VOIP versions, so check before you spend any money.
A connection between VOIP and the old telephone system can also be provided by independent suppliers.
Most (but not all) ISP's now provide an IPv6 address, which should be a static block of IPv6 addresses with a 48 bit or 64 bit binary prefix, leaving either 80 or 64 bits for the local network(s), with multiple computers and other possibly remotely controlled devices connected. Do you also need a static IPv4 address?
Some, but not all, ISP's can provide email facilities, perhaps adding an agreed user name to their own domain, although it may only be available tied to their service, so would be lost if you move to a different ISP. Consider registering your own domain name which can then be moved to another provider at any time.
Few ISP's provide domain registration and associated DNS facilities for domestic customers, but may provide far more for commercial customers at commercial rates.
There is further information more relevant to computer use under
Free Open Source Computer Operating Systems and Software
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