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local exchange (LEX)

The local exchange (OVSt), Local Exchange (LEX), forms the lowest hierarchical level in the long-distance network hierarchy. It is an exchange node of a local network in the public telephone network. Such a node, which forms the end point for the access lines of end users and companies, is connected to the node exch

anges (KVSt) located higher up in the hierarchy. These local exchanges typically supply an area with subscriber lines within a radius of 3 to 5 km. The subscriber lines, the local loops, are connected in a star configuration in the local exchange to a distribution frame. Several local exchange nodes can be combined to form a local network, which is usually based on political city and municipal boundaries and whose subscribers can be reached under a common local network code

(e.g. 0221 for Cologne). In addition, the local exchange supports the cross-local long-distance network with the long-distance exchanges

.How the structure of the local network looks in detail depends on

theswitching technology


While in the analoguetelephone network there is a direct connection between the local exchange code and the network structure, this is not necessarily the case in digitally operating local networks. Here, the local exchanges form the subscriber exchanges

, each of which serves an area and, in contrast to analogue local networks, can also extend over different local networks

Cable distribution in the local network

Cable distribution in the local network

The cabling structure from

the local

exchange to the subscriber

From the local exchange, a main cable, which consists of 400 to 600 copper pairs and can be several kilometers long, goes to the cable branch. From there, it goes via the branch cable, which consists of up to 100 copper twisted pairs, to the terminal, which is installed near the subscriber. It then travels via the terminal line to the subscriber connection box.

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Englisch: local exchange - LEX
Updated at: 11.08.2018
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