Basic connection
The basic connection is the standard connection to the digital ISDN telecommunications network. Common abbreviations for the basic connection are: BA, BAs and BRI ( basic rate interface ). It is mainly used by private customers or smaller companies. At the end of 2006 there were 12.65 million basic connections in Germany; at the end of 2015 there were still 6.13 million. Larger companies with high simultaneous telephone traffic usually use the primary rate connection instead .
Channels and data transfer rates
A basic connection offers two user channels ( B channels , from English bearer ) with 64 kbit / s each and a signaling channel ( D channel , from English data ) with 16 kbit / s. The net data transfer rate is: 2 × 64 kbit / s + 16 kbit / s = 144 kbit / s.
Subsections
The basic connection consists of two sections:
- the subscriber line (TAL) between the local exchange (or the remote peripheral unit ) and the NTBA ( network termination ) in the house. It is usually a U K0 interface consists of a copper - twisted pair and is owned by the network operator (eg the. Deutsche Telekom , Versatel ).
- the in-house cabling, which is designed as a bus and connects the end devices with the NTBA. It is called the S 0 bus and consists of two twin wires. It belongs to the subscriber who is responsible for its function.
Operating modes
Multi-device connection
The point to multipoint is the most widespread operating mode in private households. Several terminal devices (TE) can be connected directly to the S 0 bus, which (with a few exceptions) are dynamically assigned up to eight Terminal Endpoint Identifiers (TEIs) from the value range 64 to 127 by the exchange . In Germany, up to ten separate telephone numbers ( MSN ) are permanently assigned to the basic connection in multi-device operation , usually three.
System connection
Only one device (usually a telephone system ) can be connected to the system connection (point to point) . The end device is connected to the S 0 bus and receives the defined TEI value 0. Due to the different TEIs, no devices can be operated in the system connection operating mode that are intended for the multi-device connection operating mode . With the system connection, a "core number" is assigned to which the subscriber can add extensions from a specified range. Several basic connections with a common body number can also be operated here. This increases the capacity of the shared connection and at the same time enables more effective use, since every basic connection can transmit every call.
Multi-device system connection
The multi-device system connection is a special Austrian version that is rarely offered today due to the lack of hardware with Austrian firmware . With the appropriate telephone systems, several telephone numbers can be assigned to a basic connection (for example: private / company) and still be dialed through to different employees. The possibilities of the first two variants are also given here in total, for example different night and diversion circuits depending on the phone number. The elimination of this variant is justified with EU guidelines for the standardization of the systems.
Individual evidence
- ↑ Bundesnetzagentur annual report 2016. March 7, 2017, p. 54 , accessed on June 7, 2017 .
- ↑ ITU-T I.430 Integrated Services Digital Network (ISDN) - Basic Rate User-Network Interface - Layer 1 Specification, chap. 5
- ↑ ISDN - The Technology of Networks, Hüthig Verlag, p. 208
- ^ ISDN - The new telecommunications network of the Deutsche Bundespost Telekom, RvDecker's Taschenbuch Telekommunikation, TTK RvDecker's Verlag Osnabrück, 4th edition, p. 81
- ↑ ITU-T Q.921 Series Q: Switching And Signaling Digital subscriber Signaling System No. 1 - Data link layer, chap. 3.3