ISDN card
An ISDN card is a plug-in card for a computer that connects its system bus to ISDN .
ISDN cards are mainly used in hosts of routers used, for example, for telephone systems . Before the advent of DSL and local area networks , they were also popular in personal computers . The CAPI forms a software interface to application programs .
Active and passive ISDN cards
Active ISDN cards have a processor that handles the signal processing. With passive ISDN cards, the main processor of the computer takes over this task. Such ISDN cards are only intended for use with personal computers.
Connection options to the computer
ISDN cards are available for different connection variants. The PCI standard is more widespread than manufacturer-specific interfaces ; it used to be the ISA standard .
Versions based on the PCMCIA standard have not found widespread use, nor have the same technology in remote housings that has existed since the introduction of USB . The former have found a successor in UMTS data cards that is more appropriate for portable devices. The latter were overtaken by development, as the technology was integrated on the motherboards of inexpensive routers.
In the professional sector there are also devices that are addressed via one or more serial interfaces or via a serial multiplexer.
Connectivity to ISDN
The cards are usually connected to ISDN using an RJ-45 patch cable. In some cases, however, special cables are also used, for example SUB-D 9 on RJ connectors .
In addition to simple cards for a basic connection with two user channels , cards for several basic connections or a primary rate connection with 30 user channels are available. The user channels of 64 kbit / s each can be bundled depending on the data transmission rate required.
Manufacturer
AVM
The AVM GmbH is a German manufacturer with the A1-card and the Fritz-Card was known. In contrast to these, the B1 card is an active ISDN card. At the beginning of the 21st century, the company also offered ISDN cards for more than one basic connection.
Cisco
Manufacturers of professional routers such as Cisco have included corresponding plug-in cards in their range of interface modules since the introduction of ISDN. However, they only fit into the devices of the respective manufacturer.
Gerdes AG
With the PrimuX product line , Gerdes AG , founded in 1989, offers a wide range of ISDN cards for the smallest private to the most demanding professional applications. Adapter models for 2 to 120 channels are available in the versions USB, PCI, PCI-Express, Compact-PCI, SIP or VPX.
HST
HST High Soft Tech GmbH , founded in Hamburg in 1992, sells ISDN cards under the name Saphir .
ITK / Digi International
The cards from this company date from the early days of ISDN use. After the takeover by Digi International , the ISDN products disappeared from the market. Today you can find Digi International mainly in the professional sector and in line / system construction.
Xircom
Xircom brought PCMCIA cards to the market in the early 1990s that had both ISDN and modem functionality. A network card was even added later. In order to avoid the "cable clutter" associated with this, all connections were integrated in a double-height card.
ZyXEL
In the mid-1990s, ZyXEL developed a modem that could use an extended AT command set to set up both analog and digital (ISDN) connections. As was common at the time, this device was connected via a buffered serial port ( RS-232 ).
literature
- Hubert Zitt: ISDN & DSL for PC and telephone. Verlag Markt + Technik, Munich 2005, ISBN 3-8272-6987-3 .
- Thomas Joos: PC networks. Verlag Markt + Technik, Munich 2008, ISBN 978-3-8272-4386-7 .
- Jim Van Meggelen, Leif Madsen, Jared Smith: Internet Telephony with Asterisk. 1st edition. O'Reilly Verlag, 2006, ISBN 3-89721-445-8 .
- Christian Immler: The PC manual. Verlag Markt + Technik, Munich 2007, ISBN 978-3-8272-4265-5 .
- Axel Viereck, Bernhard Sonderhüsken: Information technology in practice. 1st edition. BG Teubner Verlag, Stuttgart 2001, ISBN 3-519-02971-5 .
- Ingo Lackerbauer: Internet. Verlag Markt + Technik, Munich 2007, ISBN 978-3-8272-6827-3 .