Integrated Services Digital Network (ISDN) is a set of standards for digital transmission over different media created by the Consultative Committee for International Telegraph and Telephone (CCITT) and International Telecommunication Union (ITU). As a dial-on-demand service, it has fast call setup and low latency as well as the ability to carry high-quality voice, data, and video transmissions. ISDN is also a circuit-switched service that can be used on both multipoint and point-to-point connections.
You configure two types of interfaces for ISDN service: a physical interface and a logical interface called the dialer interface.
ISDN provides a Services Router with a backup connection for network interfaces.
Each USB physical interface uses the naming convention umd-usb-slot-number.
The dialer interface, dln, is a logical interface for configuring dialing properties for USB modem connections. The interface can be configured in two modes:
The dialer interface cannot be configured simultaneously in the following modes: