Juniper Networks J-Series manual USB Modem Overview, USB Modem Interfaces, USB Modem Terminology

J-series™ Services Router Administration Guide

Table 22: USB Modem Terminology

Term	Definition
caller ID	Telephone number of the caller on the remote end of a USB modem
	connection, used to dial in and also to identify the caller. Multiple caller
	IDs can be configured on a dialer interface. During dial-in, the router
	matches the incoming call's caller ID against the caller IDs configured
	on its dialer interfaces. Each dialer interface accepts calls from only
	callers whose caller IDs are configured on it.
dialer interface (dl)	Logical interface for configuring dialing properties for a USB modem
	connection.
dial-in	Feature that enables J-series Services Routers to receive calls from the
	remote end of a USB modem connection. The remote end of the USB
	modem call might be a service provider, a corporate central location,
	or a customer premises equipment (CPE) branch office. All incoming
	calls can be verified against caller IDs configured on the router's dialer
	interface.
Microcom Networking Protocol (MNP)	Protocol that provides error correction and data compression for
	asynchronous modem transmission.

USB Modem Overview

A USB modem connects to a Services Router through modem interfaces that you configure. The router applies its own modem AT commands to initialize the attached modem. Modem setup requires that you connect and configure the USB modem at the router and the modem at the user end of the network.

■USB Modem Interfaces on page 30

■How a Services Router Initializes USB Modems on page 31

■USB Modem Connection and Configuration Overview on page 32

USB Modem Interfaces

You configure two types of interfaces for USB modem connectivity: a physical interface and a logical interface called the dialer interface:

■The USB modem physical interface uses the naming convention umd0. The Services Router creates this interface when a USB modem is connected to the USB port.

■The dialer interface, dln, is a logical interface for configuring dialing properties for USB modem connections.

See the interface naming conventions in the J-series Services Router Basic LAN and WAN Access Configuration Guide.

The following rules apply when you configure dialer interfaces for USB modem connections:

30■ USB Modem Overview