If ISDN used digital telephone line, why does it still need a modem? Is the modem used to convert the signal from computers into the format signal of ISDN service or what? -
![TIL the famous sound of dial-up is the "handshake" between the modem and the Internet Service Provider before translating internet data into soundwaves. : r/todayilearned TIL the famous sound of dial-up is the "handshake" between the modem and the Internet Service Provider before translating internet data into soundwaves. : r/todayilearned](https://external-preview.redd.it/fFQZzwSHmNvBDooHY8N02JJIzu5WD3yYKkZw32VE5IU.jpg?width=640&crop=smart&auto=webp&s=bdc088cdfffce6bab6fbff33f984361baaaffb6d)
TIL the famous sound of dial-up is the "handshake" between the modem and the Internet Service Provider before translating internet data into soundwaves. : r/todayilearned
![NT-IP | Enhanced ISDN Network Termination Device for Internet Access and Analogue Phones | Aethra, Inc. | AV-iQ NT-IP | Enhanced ISDN Network Termination Device for Internet Access and Analogue Phones | Aethra, Inc. | AV-iQ](https://cdn-images.av-iq.com/products/enlarge/NT-IP.jpg)