Telephone Engineers – The Boring Technical Stuff

A domestic single British telephone line installation has just one master socket or line box in the premises, that is provided by BT or another service providers: this socket is the demarcation point between your customer-owned and maintained on-premises wiring, and the telephone network.

NTE5 line Box


For installations using the NTE-5 line box, the demarcation point is actually within the socket: the lower half of the front plate and associated wiring is the customer’s, while the permanent wiring on the non-removable section behind this, remains the responsibility of the service provider. Customers usually are not permitted to access the telephone wiring inside a master socket without a removable lower section.
Removable plate, recently NTE5 sockets have been fitted in place of master sockets. These possess a front plate where the lower-half is removable so allowing customer’s access to the terminals required for connecting internal extension sockets; it also provides access to a test jack, to determine if telephone line faults are due to the customer’s wiring or BT’s. The removable panel also allows the external phone line to be easily disconnected from the internal wiring, provided the wiring on the premises has been correctly carried out.
Telephone Engineers


Identifing the Fault


Since BT does not have a monopoly of internal wiring, they charge a substantial amount ifyour fault reported to them turns out to be in the customer’s internal/domestic wiring. It is therefore important for the customer to have the facility to check on whether any problem

or fault is due to their internal wiring/equipment or externally in BT’s cabling or systems. Since the NTE5 socket represents the official
demarcation point between the internal/domestic wiring (at the removable front of the socket which is the customer’s responsibility) and the external telephone line/cabling fixed at the rear (that is BT’s responsibility) the physical disconnection of the two wirings (made possible with the NTE5′s removable front plate) is crucial in pinpointing faults and allocating responsibility for their rectification hence contacting independent telephone engineers would problably be the better option.


To use Broadband internet services simultaneously with voice telephony, it is vital to use a DSL filter. This is basically two filters, which divide the single line into two discrete channels. Enough bandwidth is retained for voice telephony and the majority is used for high speed data. All phones must be connected using a filter (either a separate filter for every phone or one filter covering numerous phones) to stop interference between your phones and the DSL signal. Where the data transmission is still unduly audible, using two DSL filters, daisychained in tandem, will eliminate the problem.

The DSL modem connects directly to the phone line (most DSL filters possess a socket marked DSL that connects directly through to the incoming phone line). The ringer wire is unnecessary in unfiltered parts of the wiring and its removal can often improve performance and reliability of the broadband service. When ADSL was first introduced in england it was installed by telephone engineers who replaced the front part of the NTE5 (if the property still had an old style master socket it would be replaced with an NTE5) with one containing a filter. Any hardwired phone extensions were disconnected from the original front part and connected to filtered terminals on the back of the filter.In 2008 BT trialed and launched their ‘IPlate’; the “I” is for interstitial, as it is installed between the socket and the front panel. This plate is fitted by the client in the NTE 5 and reduces interference carried by the 3rd (bell) wire. The reduced interference in some cases allows faster broadband speeds.