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Telephones and Broadband

The analogue Public Service Telephone Network (PSTN), sometimes known as the Plain Old Telephone System (POTS) 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. BT are currently required to provide enough battery or other backup to power the entire telephone system for at least 24 hours.
Later telephones used Dual Tone Multiple Frequency (DTMF) dialling which could be passed through amplifiers, repeaters, and switches, and enabled automatic remote routing. Tones could be sent while a button is pushed.
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.

The maximum possible data rate depends on the basic carrier frequency together with the available range of usable frequencies (bandwidth), so is limited by the system, connections, and equipment in use.

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 as suitable for both VDSL and ADSL with the flat-front NTE5-A at around £5.00 + 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 from includes 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.

Dedicated low power line-of-sight radio links using highly directional transmitter and receiver aerials giving a beam angle of around 0.5 degrees with dedicated frequencies 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. The dish can even be used for two channels from the same frequency band at the same time, optionally one transmit and the other receive using a precision beam circulator which can totally separate the two channels.
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. The frequencies allocated to WiFi are congested and busy, while the currently popular broadband over ordinary mains wiring is notorious for causing severe interference all round. There is a legal limit to the amount of WiFi power transmitted, although directional aerials can help, so some modems provide a mini aerial array which can be angled for the best result.
WiFi also depends on the capabilities of the equipment at both ends of a WiFi connection. The international standards include several variants of IEEE 802.11, including 802.11e, 802.11ac, and 802.11ax. WiFi 6 can make optimum use of any locally less cluttered channels by sending variable size data blocks over multiple channels if the most recent hardware and software are available at both ends of the wireless link.
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.

Gigabit ethernet uses four twisted copper pairs, although full duplex working can double the maximum data rate by enabling each pair to carry data in either direction.
Copper twisted pair ethernet cables also suffer from signal loss with distance. Cat6 cable is generally recommended as future-proof for new installations, although there may be no obvious improvement over older specifications for short local network cable runs.

Most (but not all) ISP's now provide an IPv6 address, giving a total of 128 binary bits for each interface, which should be a static block of IPv6 addresses with a 64 bit or the recommended 48 bit binary prefix, leaving either 64 or 80 bits for the local network(s), with multiple computers and other, possibly remotely controlled, devices connected. Do you also need a static 32 bit IPv4 address?

A local network may already connect using gigabit ethernet, but expect more problems as network data rates increase in the future.

If and when Fibre To The House FTTH or 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

The website has already reported promising research results. ORCA computing in west London have demonstrated a small optical quantum computer device working at room temperature, with the possibility of huge computer speed increases.

You can "Register an Interest" in getting FTTP via several websites. You may wish to check whether a battery backup will be provided to power the modem and any other distribution equipment, and whether the batteries will be replaced regularly, even if only to maintain a telephone connection. Areas liable to suffer power supply problems have found that they can lose connection, and are unable to charge mobile phones until local power is restored. Note that a "UPS" may only be designed to power a computer for long enough to safely close open files and shutdown the computer to prevent data loss. 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 ""

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.

A new fibre connection will normally bring a static IPv6 address prefix, with the option of huge numbers of static addresses and additional services.

The locations of networks and devices throughout the internet are found using binary addresses, and blocks of addresses are issued to Internet Service Providers for distribution to their customers. IPv6 uses a 128-bit binary address.
The first 64 bits specify the network, while the last 64 bits identify an individual interface within a network, with theoretically up to 2^64 individual addresses per network.
Block size is set by the number of leading binary address bits, and the not-for-profit RIPE NCC ( responsible for the European distribution issued their "Best Current Operational Practice for Operators" (BCOP) advice regarding the allocation of IPv6 128-bit addresses.
There are growing requirements for multiple static network allocations for all customers, and RIPE recommends that each customer should receive a 48-bit static prefix (/48), with all the remaining bits available for customer use, allowing up to 2^16 static (permanent) local network addresses, and strongly discourages a static prefix greater than 56-bits (/56) even for domestic customers, which would allow 2^8 (=32) static local network addresses.
There is not expected to be any shortage of IPv6 addresses for 480 years, even if none are re-used.
ISP's are required to record all allocations, together with the precise times of any changes, for security purposes, so static allocations reduce the logging requirements.

It appears that some providers, including who are installing fibre networks near my house, are not currently following this advice for any except business customers, and instead provide a dynamic 64-bit (/64) prefix, with a preferred lifetime only around a week which will probably change at each and every disruption of the connection.

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 Analogue Telephone Adapter (ATA). You may be used to having multiple analogue telephone extensions, but check that the ATA is able to drive more than a just single telephone. A DECT telephone base system could be used to supply onward connections to up to six handsets. 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. Examine the terms and conditions for any restrictions on use or connections between VOIP and the old copper system.

Dedicated VOIP, and hybrid VOIP plus Analogue, phones are now available.

Voice Over IP (VOIP) is carried as digital internet data, and automatic routing information is sent as coded messages, with no need for DTMF. Any DTMF tones are detected and converted to code ready for routing, while any additional code that remains and is not required for initial routing is replaced by new DTMF after routing is complete.
Current specifications for DTMF include 1.5% frequency tolerance, minimum 65 milliseconds, maximum 90 milliseconds, with minimum 65 milliseconds silence before and after the tones. A destination PABX may request a button push to select the required department or service, but it must now be able to detect the replacement DTMF, and holding the button down will not send a longer DTMF tone.

The internet is open, and subject to attack, and there is no exception for VOIP systems, so security is important. System providers are aware of the problems and take precautions.

Asterisk is a complete software telephone exchange system available via Free Open Source Software (FOSS) distributions such as Debian. Either use the standard computer audio facilities with headphones to maintain separation between send and receive, or adapter cards which provide a link between the computer and analogue telephones.

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.

You will require a Domain Name Service (DNS) to supply a domain name to IP address index. Some internet service providers maintain their own DNS servers, possibly with the option of filtering and omitting some addresses for security or other reasons.
CommunityFibre do not appear to provide a Domain Name Service (DNS) but recommend or provided by Google. However you may prefer to use an alternative DNS. , , and are provided by
Cisco provide either Free or Subscription DNS with security protection, see
If you are a commercial user concerned about security, consider a router with security controlled by the Cisco Meraki system which can filter both incoming and outgoing traffic.
There are internet reference sites which list addresses known to be a security risk for use by anti-virus or spamassassin protection software.

Few ISP's provide domain registration and associated DNS facilities for domestic customers, but may provide far more for commercial customers at commercial rates.

The fibre termination unit, modem, VOIP adapter, and any ethernet distribution switch, will probably all require their own separate power supply, often a low power plug top adapter, so some kind of mains distribution will be required. Some power adapter units have output cables which require clearance on the opposite side from normal mains plugs, so may require a single row 13 Amp distribution unit. provide information for installers and developers on their website.

There is further information more relevant to computer use under
Free Open Source Computer Operating Systems and Software

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