ISDN Digital Subscriber Line (IDSL)


Developed by Ascend Communications (acquired by Lucent Technologies), ISDN Digital Subscriber Line (IDSL) transmits data digitally across existing ISDN lines, at a rate of 128 Kbps. The benefits of IDSL over ISDN are that the former service offers always-on connections, transmits data via a data network rather than the phone company’s voice network, and avoids per-call fees by being billed at a flat-rate.