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USB Modem Interface Overview
USB Modem Configuration Overview
Example: Configuring a USB Modem Interface
Example: Configuring a Dialer Interface
Example: Configuring a Dialer Interface for USB Modem Dial-In
Configuring a Dial-Up Modem Connection Remotely
Connecting to the Device Remotely
Modifying USB Modem Initialization Commands
Resetting USB Modems

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USB Modems for Remote Management of Security Devices

date_range 30-Nov-23

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Junos OS allows the use of USB modems for remote management on SRX Series Firewall. You can use Telnet or SSH to connect to the device from a remote location through two modems over a telephone network. For more information, read this topic.

USB Modem Interface Overview

Juniper Networks SRX Series Firewalls support the use of USB modems for remote management. You can use Telnet or SSH to connect to the device from a remote location through two modems over a telephone network. The USB modem is connected to the USB port on the device, and a second modem is connected to a remote management device such as a PC or laptop computer.

Note:

USB modems are no longer supported for dial backup on SRX300, SRX320, SRX340, SRX345, SRX380, and SRX550HM devices.

You can configure your device to fail over to a USB modem connection when the primary Internet connection experiences interruption.

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

You use either the J-Web configuration editor or CLI configuration editor to configure the USB modem and its supporting dialer interfaces.

Note:

Low-latency traffic such as VoIP traffic is not supported over USB modem connections.

Note:

We recommend using a US Robotics USB 56k V.92 Modem, model number USR Model 5637.

USB Modem Interfaces
Dialer Interface Rules
How the Device Initializes USB Modems

USB Modem Interfaces

You configure two types of interfaces for USB modem connectivity:

A physical interface which uses the naming convention umd0. The device creates this interface when a USB modem is connected to the USB port.
A logical interface called the dialer interface. You use the dialer interface, dln, to configure dialing properties for USB modem connections. The dialer interface can be configured using Point-to-Point Protocol (PPP) encapsulation. You can also configure the dialer interface to support authentication protocols—PPP Challenge Handshake (CHAP) or Password Authentication Protocol (PAP). You can configure multiple dialer interfaces for different functions on the device. After configuring the dialer interface, you must configure a backup method such as a dialer backup, a dialer filter, or a dialer watch.

The USB modem provides a dial-in remote management interface, and supports dialer interface features by sharing the same dial pool as a dialer interface. The dial pool allows the logical dialer interface and the physical interface to be bound together dynamically on a per-call basis. You can configure the USB modem to operate either as a dial-in console for management or as a dial-in WAN backup interface. Dialer pool priority has a range from 1 to 255, with 1 designating the lowest priority interfaces and 255 designating the highest priority interfaces.

Dialer Interface Rules

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

The dialer interface must be configured to use PPP encapsulation. You cannot configure Cisco High-Level Data Link Control (HDLC) or Multilink PPP (MLPPP) encapsulation on dialer interfaces.
The dialer interface cannot be configured as a constituent link in a multilink bundle.
The dialer interface can perform backup, dialer filter, and dialer watch functions, but these operations are mutually exclusive. You can configure a single dialer interface to operate in only one of the following ways:
- As a backup interface—for one primary interface
- As a dialer filter
- As a dialer watch interface

The backup dialer interfaces are activated only when the primary interface fails. USB modem backup connectivity is supported on all interfaces except lsq-0/0/0.

The dial-on-demand routing backup method allows a USB modem connection to be activated only when network traffic configured as an “interesting packet” arrives on the network. Once the network traffic is sent, an inactivity timer is triggered and the connection is closed. You define an interesting packet using the dialer filter feature of the device. To configure dial-on-demand routing backup using a dialer filter, you first configure the dialer filter and then apply the filter to the dialer interface.

Dialer watch is a backup method that integrates backup dialing with routing capabilities and provides reliable connectivity without relying on a dialer filter to trigger outgoing USB modem connections. With dialer watch, the device monitors the existence of a specified route. If the route disappears, the dialer interface initiates the USB modem connection as a backup connection.

How the Device Initializes USB Modems

When you connect the USB modem to the USB port on the device, the device applies the modem AT commands configured in the init-command-string command to the initialization commands on the modem.

If you do not configure modem AT commands for the init-command-string command, the device applies the following default sequence of initialization commands to the modem: AT S7=45 S0=0 V1 X4 &C1 E0 Q0 &Q8 %C0. Table 1 describes the commands. For more information about these commands, see the documentation for your modem.

Table 1: Default Modem Initialization Commands
Modem Command	Description
`AT`	Attention. Informs the modem that a command follows.
`S7=45`	Instructs the modem to wait 45 seconds for a telecommunications service provider (carrier) signal before terminating the call.
`S0=0`	Disables the auto answer feature, whereby the modem automatically answers calls.
`V1`	Displays result codes as words.
`&C1`	Disables reset of the modem when it loses the carrier signal.
`E0`	Disables the display on the local terminal of commands issued to the modem from the local terminal.
`Q0`	Enables the display of result codes.
`&Q8`	Enables Microcom Networking Protocol (MNP) error control mode.
`%C0`	Disables data compression.

When the device applies the modem AT commands in the init-command-string command or the default sequence of initialization commands to the modem, it compares them to the initialization commands already configured on the modem and makes the following changes:

If the commands are the same, the device overrides existing modem values that do not match. For example, if the initialization commands on the modem include S0=0 and the device’s init-command-string command includes S0=2, the device applies S0=2.
If the initialization commands on the modem do not include a command in the device’s init-command-string command, the device adds it. For example, if the init-command-string command includes the command L2, but the modem commands do not include it, the device adds L2 to the initialization commands configured on the modem.

Note:

On SRX210 devices, the USB modem interface can handle bidirectional traffic of up to 19 Kbps. On oversubscription of this amount (that is, bidirectional traffic of 20 Kbps or above), keepalives do not get exchanged, and the interface goes down. (Platform support depends on the Junos OS release in your installation.)

USB Modem Configuration Overview

Note:

USB modems are no longer supported for dial backup on SRX300, SRX320, SRX340, and SRX345 devices.

Before you begin:

Install device hardware. For more information, see the Getting Started Guide for your device.
Establish basic connectivity. For more information, see the Getting Started Guide for your device.
Order a US Robotics USB 56k V.92 Modem, model number USR Model 5637 (http://www.usr.com/).
Order a public switched telephone network (PSTN) line from your telecommunications service provider. Contact your service provider for more information.
Connect the USB modem to the device's USB port.

Note:
When you connect the USB modem to the USB port on the device, the USB modem is initialized with the modem initialization string configured for the USB modem interface on the device.
1. Plug the modem into the USB port.
2. Connect the modem to your telephone network.

Suppose you have a branch office router and a head office router each with a USB modem interface and a dialer interface. This example shows you how to establish a backup connection between the branch office and head office routers. See Table 2 for a summarized description of the procedure.

Table 2: Configuring Branch Office and Head Office Routers for USB Modem Backup Connectivity
Router Location	Configuration Requirement	Procedure
Branch Office	Configure the logical dialer interface on the branch office router for USB modem dial backup.	To configure the logical dialer interface, see Example: Configuring a USB Modem Interface.
Branch Office	Configure the dialer interface `dl0` on the branch office router using one of the following backup methods: Configure the dialer interface `dl0` as the backup interface on the branch office router's primary T1 interface `t1-1/0/0`. Configure a dialer filter on the branch office router's dialer interface. Configure a dialer watch on the branch office router's dialer interface.	Configure the dialer interface using one of the following backup methods: To configure `dl0` as a backup for `t1-1/0/0` see Example: Configuring Dialer Interfaces and Backup Methods for USB Modem Dial Backup. To configure a dialer filter on `dl0`, see Example: Configuring Dialer Interfaces and Backup Methods for USB Modem Dial Backup. To configure a dialer watch on `dl0`, see Example: Configuring Dialer Interfaces and Backup Methods for USB Modem Dial Backup.
Head Office	Configure dial-in on the dialer interface `dl0` on the head office router.	To configure dial-in on the head office router, see Example: Configuring a Dialer Interface for USB Modem Dial-In.

If the dialer interface is configured to accept only calls from a specific caller ID, the device matches the incoming call's caller ID against the caller IDs configured on its dialer interfaces. If an exact match is not found and the incoming call's caller ID has more digits than the configured caller IDs, the device performs a right-to-left match of the incoming call's caller ID with the configured caller IDs and accepts the incoming call if a match is found. For example, if the incoming call's caller ID is 4085321091 and the caller ID configured on a dialer interface is 5321091, the incoming call is accepted. Each dialer interface accepts calls from only callers whose caller IDs are configured on it.

See Table 3 for a list of available incoming map options.

Table 3: Incoming Map Options
Option	Description
`accept-all`	Dialer interface accepts all incoming calls. You can configure the `accept-all` option for only one of the dialer interfaces associated with a USB modem physical interface. The dialer interface with the `accept-all` option configured is used only if the incoming call's caller ID does not match the caller IDs configured on other dialer interfaces.
`caller`	Dialer interface accepts calls from a specific caller ID. You can configure a maximum of 15 caller IDs per dialer interface. The same caller ID must not be configured on different dialer interfaces. However, you can configure caller IDs with more or fewer digits on different dialer interfaces. For example, you can configure the caller IDs 14085551515, 4085551515, and 5551515 on different dialer interfaces.

You configure dialer interfaces to support PAP. PAP allows a simple method for a peer to establish its identity using a two-way handshake during initial link establishment. After the link is established, an ID and password pair are repeatedly sent by the peer to the authenticator until authentication is acknowledged or the connection is terminated.

Example: Configuring a USB Modem Interface

This example shows how to configure a USB modem interface for dial backup.

Note:

USB modems are no longer supported for dial backup on SRX300, SRX320, SRX340, and SRX345 devices.

Requirements
Overview
Configuration
Verification

Requirements

No special configuration beyond device initialization is required before configuring this feature.

Overview

In this example, you create an interface called as umd0 for USB modem connectivity and set the dialer pool priority to 25. You also configure a modem initialization string to autoanswer after a specified number of rings. The default modem initialization string is AT S7=45 S0=0 V1 X4 &C1 E0 Q0 &Q8 %C0. The modem command S0=0 disables the modem from autoanswering the calls. Finally, you set the modem to act as a dial-in WAN backup interface.

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following command, paste it into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the command into the CLI at the [edit] hierarchy level, and then enter commit from configuration mode.

content_copy zoom_out_map
set interfaces umd0 dialer-options pool usb-modem-dialer-pool priority 25
set modem-options init-command-string "ATS0=2 \n" dialin routable 

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For instructions on how to do that, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To configure a USB modem interface for dial backup:

Create an interface.
```
[edit]
user@host# edit interfaces umd0
```

Set the dialer options and priority.

content_copy zoom_out_map
[edit interfaces umd0]
user@host# set dialer-options pool usb-modem-dialer-pool priority 25

Specify the modem options.

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[edit interfaces umd0]
user@host# set modem-options init-command-string "ATS0=2 \n"

Set the modem to act as a dial-in WAN backup interface.
```
[edit interfaces umd0]
user@host# set modem-options dialin routable
```

Results

From configuration mode, confirm your configuration by entering the show interface umd0 command. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.

content_copy zoom_out_map
[edit]
    user@host# show interface umd0
modem-options {
init-command-string "ATS0=2 \n";
    dialin routable;
}
dialer-options {
    pool usb-modem-dialer-pool priority 25;
}

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Verifying the Configuration

Purpose
Action

Purpose

Verify a USB modem interface for dial backup.

Action

From configuration mode, enter the show interfaces umd0 extensive command. The output shows a summary of interface information and displays the modem status.

content_copy zoom_out_map
Physical interface:   umd0, Enabled, Physical link is Up
Interface index:      64, SNMP ifIndex: 33, Generation: 1
  Type: Async-Serial, Link-level type: PPP-Subordinate, MTU: 1504, 
Clocking: Unspecified, Speed: MODEM
  Device flags   : Present Running
  Interface flags: Point-To-Point SNMP-Traps Internal: 0x4000
  Link flags     : None
  Hold-times     : Up 0 ms, Down 0 ms
  Last flapped   : Never
  Statistics last cleared: Never
 Traffic statistics:
   Input  bytes  :                21672
   Output bytes  :                22558
   Input  packets:                 1782
   Output packets:                 1832
  Input errors:
    Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Giants: 0, Policed discards: 0, 
Resource errors: 0
  Output errors:
    Carrier transitions: 63, Errors: 0, Drops: 0, MTU errors: 0, Resource errors: 0
  MODEM status:
    Modem type                    : LT V.92 1.0 MT5634ZBA-USB-V92 Data/Fax Modem 
(Dual Config) Version 2.27m
    Initialization command string : ATS0=2
    Initialization status         : Ok
    Call status                   : Connected to 4085551515
    Call duration                 : 13429 seconds
    Call direction                : Dialin
    Baud rate                     : 33600 bps
    Most recent error code        : NO CARRIER

  Logical interface umd0.0 (Index 2) (SNMP ifIndex 34) (Generation 1)
    Flags: Point-To-Point SNMP-Traps Encapsulation: PPP-Subordinate

Example: Configuring a Dialer Interface

This example shows how to configure a logical dialer interface for an SRX300, SRX320, SRX340, or SRX345 device.

Requirements
Overview
Configuration
Verification

Requirements

Before you begin:

Install device hardware and establish basic connectivity. See the Getting Started Guide for your device.
Order a US Robotics USB 56k V.92 Modem, model number USR Model 5637, from US Robotics (http://www.usr.com/).
Order a dial-up modem for the PC or laptop computer at the remote location from where you want to connect to the device.
Order a PSTN line from your telecommunications service provider. Contact your service provider.

Overview

In this example, you configure a logical dialer interface called dl0 to establish USB connectivity. You can configure multiple dialer interfaces for different functions on the device. You add a description to differentiate among different dialer interfaces. For example, this modem is called USB-modem-remote-management. Configure PPP encapsulation and set the logical unit as 0. You then specify the name of the dialer pool as usb-modem-dialer-pool and set the source and destination IP addresses as 172.20.10.2, and 172.20.10.1, respectively.

Note:

You cannot configure Cisco High-Level Data Link Control (HDLC) or Multilink PPP (MLPPP) encapsulation on dialer interfaces used in USB modem connections.

Note:

If you configure multiple dialer interfaces, ensure that the same IP subnet address is not configured on different dialer interfaces. Configuring the same IP subnet address on multiple dialer interfaces can result in inconsistency in the route and packet loss. The device might route packets through another dialer interface with the IP subnet address instead of through the dialer interface to which the USB modem call is mapped.

Configuration

Procedure

CLI Quick Configuration
Step-by-Step Procedure
Results

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level, and then enter commit from configuration mode.

content_copy zoom_out_map
set interfaces dl0 description USB-modem-remote-management  encapsulation ppp
set interfaces dl0 unit 0 dialer-options pool usb-modem-dialer-pool 
set interfaces dl0 unit 0 family inet address 172.20.10.2 destination 172.20.10.1

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For instructions on how to do that, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To configure a logical dialer interface for the device:

Create an interface.
```
[edit]
user@host# set interfaces dl0
```

Add a description and configure PPP encapsulation.

content_copy zoom_out_map
[edit interfaces dl0]
user@host# set description USB-modem-remote-management 
user@host# set encapsulation ppp

Create the logical unit.

Note:
The logical unit number must be 0.
```
[edit interfaces dl0]
user@host# set unit 0
```
Configure the name of the dialer pool to use for USB modem connectivity.
```
[edit interfaces dl0 unit 0]
user@host# set dialer-options pool usb-modem-dialer-pool
```

Configure source and destination IP addresses for the dialer interface.

content_copy zoom_out_map
[edit interfaces dl0 unit 0]
user@host# set family inet address 172.20.10.2 destination 172.20.10.1

Results

From configuration mode, confirm your configuration by entering the show interfaces dl0 command. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.

content_copy zoom_out_map
[edit]
user@host# show interfaces dl0
description USB-modem-remote-management;
    encapsulation ppp;
    unit 0 {
    family inet {
        address 172.20.10.2/32 {
        destination 172.20.10.1;
    }
    }
    dialer-options {
        pool usb-modem-dialer-pool;
    }
}

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Verifying a Dialer Interface

Purpose
Action

Purpose

Verify that the dialer interface has been configured.

Action

From configuration mode, enter the show interfaces dl0 extensive command. The output shows a summary of dialer interface information.

content_copy zoom_out_map
Physical interface: dl0, Enabled, Physical link is Up
  Interface index: 128, SNMP ifIndex: 24, Generation: 129
  Type: 27, Link-level type: PPP, MTU: 1504, Clocking: Unspecified, Speed: Unspecified
  Device flags   : Present Running
  Interface flags: SNMP-Traps
  Link type      : Full-Duplex
  Link flags     : Keepalives
  Physical info  : Unspecified
  Hold-times     : Up 0 ms, Down 0 ms
  Current address: Unspecified, Hardware address: Unspecified
  Alternate link address: Unspecified
  Last flapped   : Never
  Statistics last cleared: Never
  Traffic statistics:
   Input  bytes  :                13859                    0 bps
   Output bytes  :                    0                    0 bps
   Input  packets:                  317                    0 pps
   Output packets:                    0                    0 pps
  Input errors:
    Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Giants: 0, Policed discards: 0, 
Resource errors: 0
  Output errors:
    Carrier transitions: 0, Errors: 0, Drops: 0, MTU errors: 0, Resource errors: 0

  Logical interface dl0.0 (Index 70) (SNMP ifIndex 75) (Generation 146)
    Description: USB-modem-remote-management
    Flags: Point-To-Point SNMP-Traps 0x4000 LinkAddress 23-0 Encapsulation: PPP
    Dialer:  
      State: Active, Dial pool: usb-modem-dialer-pool
      Dial strings: 220
      Subordinate interfaces: umd0 (Index 64)
      Activation delay: 0, Deactivation delay: 0
      Initial route check delay: 120
      Redial delay: 3
      Callback wait period: 5
      Load threshold: 0, Load interval: 60
    Bandwidth: 115200
    Traffic statistics:
     Input  bytes  :                24839
     Output bytes  :                17792
     Input  packets:                  489
     Output packets:                  340
    Local statistics:
     Input  bytes  :                10980
     Output bytes  :                17792
     Input  packets:                  172
     Output packets:                  340
    Transit statistics:
     Input  bytes  :                13859                    0 bps
     Output bytes  :                    0                    0 bps
     Input  packets:                  317                    0 pps
     Output packets:                    0                    0 pps
  LCP state: Opened 
  NCP state: inet: Opened, inet6: Not-configured, iso: Not-configured, 
mpls: Not-configured
  CHAP state: Success
    Protocol inet, MTU: 1500, Generation: 136, Route table: 0
      Flags: None   
      Addresses, Flags: Is-Preferred Is-Primary
        Destination: 172.20.10.1, Local: 172.20.10.2, Broadcast: Unspecified, 
Generation: 134

Example: Configuring a Dialer Interface for USB Modem Dial-In

This example shows how to configure a dialer interface for USB modem dial-in.

Note:

USB modems are no longer supported for dial-in to a dialer interface on SRX300, SRX320, SRX340, and SRX345 devices.

Requirements
Overview
Configuration
Verification

Requirements

No special configuration beyond device initialization is required before configuring this feature.

Overview

To enable connections to the USB modem from a remote location, you must configure the dialer interfaces set up for USB modem use to accept incoming calls. You can configure a dialer interface to accept all incoming calls or accept only calls from one or more caller IDs.

If the dialer interface is configured to accept only calls from a specific caller ID, the system matches the incoming call's caller ID against the caller IDs configured on its dialer interfaces. If an exact match is not found and the incoming call's caller ID has more digits than the configured caller IDs, the system performs a right-to-left match of the incoming call's caller ID with the configured caller IDs and accepts the incoming call if a match is found. For example, if the incoming call's caller ID is 4085550115 and the caller ID configured on a dialer interface is 5550115, the incoming call is accepted. Each dialer interface accepts calls from only callers whose caller IDs are configured on it.

You can configure the following incoming map options for the dialer interface:

accept-all—Dialer interface accepts all incoming calls.

You can configure the accept-all option for only one of the dialer interfaces associated with a USB modem physical interface. The device uses the dialer interface with the accept-all option configured only if the incoming call's caller ID does not match the caller IDs configured on other dialer interfaces.
caller—Dialer interface accepts calls from a specific caller ID— for example, 4085550115. You can configure a maximum of 15 caller IDs per dialer interface.

The same caller ID must not be configured on different dialer interfaces. However, you can configure caller IDs with more or fewer digits on different dialer interfaces. For example, you can configure the caller IDs 14085550115, 4085550115, and 5550115 on different dialer interfaces.

In this example, you configure the incoming map option as caller 4085550115 for dialer interface dl0.

Configuration

CLI Quick Configuration
Procedure

CLI Quick Configuration

content_copy zoom_out_map
set interfaces dl0 unit 0 dialer-options incoming-map caller 4085550115 

Procedure

Step-by-Step Procedure

To configure a dialer interface for USB modem dial-in:

Select a dialer interface.
```
[edit]
user@host# edit interfaces dl0
```

Configure the incoming map options.

content_copy zoom_out_map
[edit]
user@host# edit unit 0 dialer-options incoming-map caller 4085551515

If you are done configuring the device, commit the configuration.
```
[edit]
user@host# commit
```

Verification

To verify the configuration is working properly, enter the show interface dl0 command.

Configuring a Dial-Up Modem Connection Remotely

To remotely connect to the USB modem connected to the USB port on the device, you must configure a dial-up modem connection on the PC or laptop computer at your remote location. Configure the dial-up modem connection properties to disable IP header compression.

To configure a dial-up modem connection remotely:

At your remote location, connect a modem to a management device such as a PC or laptop computer.
Connect the modem to your telephone network.
On the PC or laptop computer, select Start>Settings>Control Panel>Network Connections. The Network Connections page appearts.
Click Create a new connection. The New Connection Wizard appears.
Click Next. The New Connection Wizard: Network Connection Type page appears.
Select Connect to the network at my workplace, and then click Next.
The New Connection Wizard: Network Connection page appears.
Select Dial-up connection, and then click Next. The New Connection Wizard: Connection Name page appears.
In the Company Name box, type the dial-up connection name, for example USB-modem-connect. Then, click Next. The New Connection Wizard: Phone Number to Dial page appears.
In the Phone number box, type the telephone number of the PSTN line connected to the USB modem at the device end.
Click Next twice, and then click Finish. The Connect USB-modem-connect page appears.
If CHAP is configured on the dialer interface used for the USB modem interface at the device end, type the username and password configured in the CHAP configuration in the User name and Password boxes.
Click Properties. The USB-modem-connect Properties page appears.
In the Networking tab, select Internet Protocol (TCP/IP), and then click Properties. The Internet Protocol (TCP/IP) Properties page appears.
Click Advanced. The Advanced TCP/IP Settings page appears.
Clear the Use IP header compression check box.

Connecting to the Device Remotely

To remotely connect to the device through a USB modem connected to the USB port on the device:

On the PC or laptop computer at your remote location, select Start>Settings>Control Panel>Network Connections. The Network Connections page appears.
Double-click the USB-modem-connect dial-up connection. The Connect USB-modem-connect page appears.
Click Dial to connect to the Juniper Networks device.
When the connection is complete, you can use Telnet or SSH to connect to the device.

Modifying USB Modem Initialization Commands

Note:

These instructions use Hayes-compatible modem commands to configure the modem. If your modem is not Hayes-compatible, see the documentation for your modem and enter equivalent modem commands. Applies to SRX300, SRX320, SRX340, SRX345 devices.

You can use the CLI configuration editor to override the value of an initialization command configured on the USB modem or configure additional commands for initializing USB modems.

Note:

If you modify modem initialization commands when a call is in progress, the new initialization sequence is applied on the modem only when the call ends.

You can configure the following modem AT commands to initialize the USB modem:

The command S0=2 configures the modem to automatically answer calls on the second ring.
The command L2 configures medium speaker volume on the modem.

You can insert spaces between commands.

When you configure modem commands in the CLI configuration editor, you must follow these conventions:

Use the newline character \n to indicate the end of a command sequence.
Enclose the command string in double quotation marks.

You can override the value of the S0=0 command in the initialization sequence configured on the modem and add the L2 command.

To modify the initialization commands on a USB modem:

Configure the modem AT commands to initialize the USB modem.

content_copy zoom_out_map
[edit interfaces umd0]
user@host# set modem-options init-command-string "AT S0=2 L2 \n"

If you are done configuring the device, enter commit from configuration mode.

Resetting USB Modems

For SRX300, SRX320, SRX340, and SRX345 devices, if the USB modem does not respond, you can reset the modem.

CAUTION:

If you reset the modem when a call is in progress, the call is terminated.

To reset the USB modem, in operational mode, enter the following command:

content_copy zoom_out_map
user@host> request interface modem reset umd0

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User Access and Authentication Administration Guide for Junos OS

ON THIS PAGE

USB Modems for Remote Management of Security Devices

USB Modem Interface Overview

USB Modem Interfaces

Dialer Interface Rules

How the Device Initializes USB Modems

USB Modem Configuration Overview

Example: Configuring a USB Modem Interface

Requirements

Overview

Configuration

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Verification

Verifying the Configuration

Purpose

Action

Example: Configuring a Dialer Interface

Requirements

Overview

Configuration

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Verification

Verifying a Dialer Interface

Purpose

Action

Example: Configuring a Dialer Interface for USB Modem Dial-In

Requirements

Overview

Configuration

CLI Quick Configuration

Procedure

Step-by-Step Procedure

Verification

Configuring a Dial-Up Modem Connection Remotely

Connecting to the Device Remotely

Modifying USB Modem Initialization Commands

Resetting USB Modems

Related Documentation

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