LTE Mini-PIM Overview


The LTE Mini-Physical Interface Module (Mini-PIM) provides wireless WAN support on the SRX320, SRX340, SRX345, and SRX550M (High Memory) Services Gateways. The LTE Mini-PIM operates on both 3G and 4G networks. Table 1 provides a summary of the different models of the Mini-PIM.

Table 1: LTE Mini-PIM Models



Operating Region

Frequency Band


  • LTE

  • HSPA+

  • North America

  • European Union

For LTE:

  • Bands 1 through 5, 7, 8, 12, 13, 20, 25, 26, 29, 30, and 41

For 3G (HSPA+):

  • Bands 1 through 5, and 8


  • LTE

  • HSPA+

  • Asia

  • Australia

For LTE:

  • Bands 1,3, 5, 7, 8, 18, 19, 21, 28, 38, 39, 40, and 41

For 3G (HSPA+):

  • Bands 1, 5, 6, 8, 9, and 19

Supported Features

The LTE Mini-PIM supports the following features:

  • Automatic switchover between service providers through dual SIMs—The Mini-PIM supports up to two Subscriber Identity Module (SIM) cards. Dual SIM cards allow connectivity to two different ISP networks and provide a failover mechanism when the current active network fails. Each SIM card is associated with a profile, which is used to connect to the network.

  • Multiple service provider and access point name (APN) profiles—You can configure up to 16 profiles for each SIM, although only one profile can be active at a time. The LTE Mini-PIM supports two SIM cards and so you can configure a total of 32 profiles.

  • LTE carrier aggregation—Carrier aggregation expands the LTE bandwidth by combining secondary bands, which results in increased capacity and network efficiency.

  • SIM security functions—The Mini-PIM supports security functions such as SIM lock and unlock, and PIN change.

  • Always-on, dial-on-demand, and backup modes—The Mini-PIM can be configured in three modes:

    • Always-on—The Mini-PIM connects to the 3G/4G network after booting. The connection is always maintained, as long as there are no network or connectivity problems.

    • Dial-on-demand—The Mini-PIM initiates a connection when it receives interesting traffic. You define interesting traffic using the dialer filter. To configure dial-on-demand using a dialer filter, you first configure the dialer filter and then apply the filter to the dialer interface.


      The dial-on-demand mode is supported only if the LTE mini-PIM is configured as a primary interface.

    • Backup—The Mini-PIM connects to the 3G/4G network when the primary connection fails.

  • Primary and backup interface—You can configure the LTE Mini-PIM either as a primary interface or as a backup interface.

    When configured as the primary interface, the LTE Mini-PIM supports both the Always-on and Dial-on-demand modes.

    When configured as the backup interface, the LTE Mini-PIM connects to the network only when the primary interface fails.

  • Over-the-air upgrade for modem firmware—Over-the-air (OTA) firmware upgrade enables automatic and timely upgrade of modem firmware when new firmware versions are available. The OTA upgrade can be enabled or disabled on the LTE Mini-PIM.


    OTA upgrade is disabled by default.

Understanding the LTE Physical Interface

The physical interface for the 4G LTE Mini-PIM uses the name cl-slot number/0/0, where slot number identifies the slot on the services gateway in which you insert the Mini-PIM. For example, cl-1/0/0. The Mini-PIM can be inserted in any of the Mini-PIM slots on the SRX320, SRX340, SRX345, and SRX550M Services Gateways. You configure the following properties on the physical interface:

  • A dialer pool to which the physical interface belongs and the priority of the interface in the pool.

  • Profiles for the SIM cards.

  • Radio access technology (automatic, 3G, LTE)

Understanding the LTE Logical Interface

The dialer interface, dl0, is a logical interface, which is used to trigger calls. When traffic is sent to the dl0 interface, it enables the physical interface in the dialer pool and places calls through the physical interface. The dialer interface can perform backup and dialer filter functions. You can configure the dialer interface to operate in any one of the following ways:

The following rules apply when you configure dialer interfaces:

  • You cannot configure the dialer interface as a constituent link in a multilink bundle.

  • You cannot configure any dial-in options for the dialer interface.

You configure the following for a dialer interface:

  • A dialer pool to which the physical interface belongs.

  • Dial string (destination number to be dialed).

You can also specify optional operating parameters for the dialer interface:

  • Activation delay—Number of seconds after the primary interface is down before the backup interface is activated. The default value is 0 seconds, and the maximum value is 60 seconds.

  • Deactivation delay—Number of seconds after the primary interface is up before the backup interface is deactivated. The default value is 0 seconds, and the maximum value is 60 seconds.

Class of Service on the Dialer Interface

The dialer interface has limited bandwidth, which can lead to traffic congestion. Starting with Junos OS Release 15.1X49-D100, the dialer interface supports the configuration of 4G LTE dialer interface Class of Service (CoS) parameters on SRX320, SRX340, SRX345, and SRX550M devices. The dialer interface supports the following CoS parameters:

  • Behavior aggregate and multifield classifiers

  • Policers

  • Shapers

  • Schedulers

  • Rewrite rules


The dialer interface (dl0) supports scheduling only at the physical interface queue level. As this interface does not support shaping at the logical interface level, per-unit scheduling is not supported on the dialer interface.

See Class of Service Feature Guide for Security Devices for information on configuring these parameters.