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The AT&T EX15 can be used as a primary data connection or as a backup network solution to streamline business continuity

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With the 1003-CM Plug-In modem, the EX15 can connect to a cellular network using the 4G LTE standard that best suits its given use case

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Sim Cards

Choose the cellular connection that best meets your speed, budget, fallback-network, & geographic requirements, at any time


Getting Started


What's in the Box

EX15 Inventory

EX15 Unit

U115 Welcome Card

Digi 1003-CM CORE modem

Note The CORE modem included in your box may be branded for Digi Accelerated rather than for Digi.


Cellular Antennas (4)


Power Supply Unit


Temporary Battery Pack


Ethernet Cables

1 x 18 inch
1 x 156 inch


CORE modem cover plate


Passive power-over-Ethernet injector


Mounting bracket


CM unit anchor screws


Ceiling rail clips

2 Narrow
2 Wide


Screws (2)


Drywall anchors (2)


Zipties (2)



Activate that SIM Card on your preferred AT&T Wireless plan.


Swap the inactive SIM with an activated SIM card.


Add a secondary active SIM card in SIM2 that can be used as an alternative connection.

Note the SIM slots support a standard size 2FF (mini) SIM card and the device will default to try to connect to SIM1 and failover to SIM2 if it cannot obtain a connection on SIM1. Once the device connects it will stay connected to that SIM unless there is a future connection problem.

Insert the CORE modem into the EX15 by aligning the white clip. Press the modem in and then push the white clip in until it locks firmly in place.


Secure the CORE modemwith one of the CM unit anchor screws.


Cover the installed CORE modem with the cover plate. The cover plate will snap into place.


Carefully attach the 4 antennas and note there is limited clearance so leave them straight until they are all attached. Once the antennas are attached spread them apart from each other as much as possible to limit interference. Please note you may need to overturn the antenna once to get it to stay in position.


If you intend to configure Ethernet WAN access, use an Ethernet cable to connect the EX15's 2/WAN port to a device with access to the Internet.


To provide LAN connectivity from the EX15 use an Ethernet cable to connect the EX15 1/PoE port to your primary router, SD-WAN, Firewall or PC.

Power Up


Connect the DC Power or use the included PoE injector to connect power through the 1/PoE Ethernet port (this is especially helpful to capture better signal strength outside of the equipment room).


Verify that the signal strength indicator on the front of the EX15 shows 2 or more bars, and that the LTE LED on the front of the EX15 shows either green or blue (solid or flashing) for proper operation.

Note: The flashing LTE light means the 1/PoE port does not have an Ethernet connection and will need to be addressed for proper operation.



Most of the time an active SIM card can be used to connect the device to the Internet and pull down the device’s configuration from ARMT. If there is a custom APN or no SIM card available, an Internet Ethernet connection (with DHCP) can be used to connect the EX15 2/WAN port to pull down the device configuration (a great staging option).


If you want to configure the EX15 in the local GUI, connect a PC to the 1/PoE port and go to and log into the EX155 with the user name admin and the password printed on the bottom of the label (please note that if the device has already been configured a new password may have been applied).

Ethernet port default configuration

  • Port 1 is configured as a LAN port and will issue a single passthrough IP Address using DHCP based on the IP received from the cellular connection

    Note: By default, the EX15 device is in cellular passthrough mode. This prevents clients that attach to the device's LAN port from using the device's WAN internet connection. See Enable router mode for instructions regarding how to configure the EX15 device to provide internet connectivity to more than one connected device at a time.

  • Port 2 is configured as a WAN port and will accept an IP Address from an existing local network router.