be plugged into the front. If it was desired to locate the DSL modem away from the master socket a plug-in ADSL extension kit could be purchased. BT also offered "wires-only" ADSL service and promoted the technique of using a separate plug-in filter on every socket. While both technically inferior and far less tidy than the solution BT engineers had used, it was usually adequate and was simple enough for a non-technical householder to understand. The more discerning customer can purchase a variety of hardwired filtering products, including replacement front plates for the NTE5, some of which have unfiltered as well as filtered terminals on the back to avoid the need to plug in the extension wiring that leads to the DSL modem. In 2008 BT trialled and launched their 'IPlate'; the "I" is for interstitial, as it is fitted between the socket and the front panel. This plate is fitted by the consumer inside the NTE 5 and reduces interference carried by the 3rd (bell) wire. The reduced interference allows faster broadband speeds - BT claim a speed improvement of up to 1.5 Mbit/s with a theoretical 4 Mbit/s. By November 2009 BT were calling the I-plate a "BT Broadband Accelerator". Structured cabling Structured cabling systems are general-purpose communications wires installed in offices and increasingly also homes, which can be used for several different communication technologies (analog phone, ADSL, ISDN, Ethernet, video, etc.). The most common type uses Category 5 cables (four twisted pairs with 100 ohm impedance) between 8P8C (colloquially and incorrectly called RJ45) room sockets and a central patch panel. The A and B wires of an analogue phone line appear in a structured cabling system usually on the centre pins of the 8P8C connector (pins 4 and 5; the blue/white TIA/EIA-568 pair 1 in Cat5 cables). In most other countries, those two wires are all that is needed to connect an analogue telephone. In the UK, however, many telephone circuits still have an anti-tinkle connection between the master socket and extensions on a third wire. But such a 3-wire interface is not the symmetric interface needed for balanced twisted-pair transmission lines, and therefore prone to electromagnetic interference and crosstalk with nearby other wiring. It is modern practice to remove the bell wire to rebalance the circuit and thus reduce potential interference from office or far field RF interference. The telephone is plugged at the other end