# ISDN card
**Wikidata**: [Q1654588](https://www.wikidata.org/wiki/Q1654588)  
**Source**: https://4ort.xyz/entity/isdn-card

## Summary  
An ISDN card is a type of expansion card and modem that enables digital communication over Integrated Services Digital Network (ISDN) lines, providing voice and data transmission capabilities. It combines the functions of a modem and an expansion card, allowing computers to connect to ISDN networks for faster digital connectivity compared to analog modems.  

## Key Facts  
- **Protocol**: Utilizes the Integrated Services Digital Network (ISDN) standard.  
- **Classification**: Subclass of both **modem** and **expansion card**.  
- **Related Hardware**: Examples include AVM ISDN-Controllers, a specific class of ISDN cards.  
- **Media**: Image available at [commons.wikimedia.org/wiki/Special:FilePath/AVM_ISDN_Controller_B1_v2.jpg](https://commons.wikimedia.org/wiki/Special:FilePath/AVM_ISDN_Controller_B1_v2.jpg).  
- **Commons Category**: Categorized under "ISDN cards" on Wikimedia Commons.  
- **Sitelink Count**: 2 sitelinks across Wikidata.  
- **Legacy Status**: Primarily associated with 1990s telecommunications infrastructure.  

## FAQs  
### Q: What is an ISDN card used for?  
A: An ISDN card allows computers to connect to ISDN lines for digital voice and data transmission, enabling faster connectivity than traditional analog modems.  

### Q: How does an ISDN card differ from a standard modem?  
A: Unlike analog modems, ISDN cards use digital signaling over ISDN lines, supporting simultaneous voice and data transmission at higher speeds (e.g., 64–128 kbps).  

### Q: Are ISDN cards still relevant today?  
A: ISDN cards are largely obsolete due to the decline of ISDN infrastructure, replaced by broadband technologies like DSL, fiber optics, and wireless networks.  

## Why It Matters  
The ISDN card played a critical role in transitioning from analog to digital telecommunications in the 1990s. It solved the problem of slow modem speeds by leveraging ISDN’s digital infrastructure, enabling applications like video conferencing, VoIP, and high-speed internet access. While rendered obsolete by newer technologies, it bridged the gap between early dial-up systems and modern broadband, influencing the development of telecommunication standards. Its integration of voice and data services also highlighted the potential for unified communications, a concept still relevant today.  

## Notable For  
- **Digital Connectivity**: Provided faster, digital transmission compared to analog modems.  
- **AVM ISDN-Controllers**: A notable implementation of ISDN card technology, documented in hardware archives.  
- **Legacy Telecommunications**: Key component of 1990s enterprise and consumer ISDN adoption.  
- **Multifunction Design**: Combined modem and expansion card functionalities in a single device.  

## Body  
### Definition and Function  
An ISDN card is a hardware component that connects to a computer’s expansion slot, integrating modem capabilities to support ISDN protocols. It facilitates digital communication over ISDN lines, which use separate voice and data channels for improved performance.  

### Technical Specifications  
- **Protocol**: Implements the Integrated Services Digital Network standard (ITU-T Q.931).  
- **Data Rates**: Supports speeds up to 128 kbps via dual 64 kbps B-channels.  
- **Subclass**: Categorized as both a **modem** (enabling network connectivity) and an **expansion card** (adding hardware functionality).  

### Related Technologies  
- **AVM ISDN-Controllers**: A specific class of ISDN cards manufactured by AVM, a Dutch company, with documented models like the B1 v2.  
- **Modem Evolution**: Contrasts with analog modems (e.g., 56k) by using digital signaling, reducing latency and improving reliability.  

### Historical Context  
- **Peak Usage**: Prominent in the 1990s for applications requiring high-speed digital connectivity, such as corporate networks and early telemedicine systems.  
- **Decline**: Phased out in the 2000s as ADSL, cable modems, and fiber-optic technologies became prevalent.  

### Legacy  
- **Standards Influence**: Contributed to the development of broadband standards by demonstrating demand for digital telecommunications infrastructure.  
- **Preservation**: Documented in Wikimedia Commons under the "ISDN cards" category, with limited but specific historical interest.