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Requirements

  • A Linux device with a cellular modem and an active Hologram SIM.
  • ModemManager installed, which provides the mmcli command.
  • Access to your Hologram dashboard for the SIM you are testing.
  • Permission to run sudo on the device, which is required to create, send, and delete messages.

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Verify the modem is connected

Before testing SMS, confirm the modem is attached and connected on LTE: 
mmcli -m any
Check the following fields in the output:
  • Status > state: should be connected or enabled
  • Status > access tech: should be lte (in regions that still support 2G or 3G, gsm-umts or others may also work)
  • 3GPP > operator name: should be Hologram or the actual mobile network operator
  • 3GPP > registration: should be roaming or home
  • 3GPP EPS > ue mode of operation: should be csps-2 (combined CS/PS, which is required for SMS)
  • 3GPP > packet service state: should be attached
mmcli output showing modem status, access technology, and 3GPP registration fields
If ue mode of operation is not csps-2, SMS may not work. Check your modem’s UE mode configuration.

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Send an SMS message to the device from your dashboard

1

Send a test message

In your dashboard, navigate to the SIM and use the Manage SIM menu to Send message to SIM and send a test message to the SIM.
2

Confirm the events in Event history

After sending, open the Events tab for the SIM to view event history. You should see two events:
  1. The message sent to the device, “To SIM”. In the example below, the message body is g2-sms-20260623 with an event type of Inbound SMS (_SMS_DT_ event tag).
  2. A delivery confirmation sent back to Hologram, “From SIM”. In the example below, the message body is SMS with an event type of Inbound SMS delivered (_SMS_DT_DELIVERED_ event tag).
Dashboard Event History showing To SIM and From SIM events for the test message

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Verify the message was received by the device

List the messages stored on the modem: 
mmcli -m any --messaging-list-sms
Inspect a received message by its index: 
mmcli -s 12
Messages from Hologram arrive from the number assigned to the Hologram short or long code. The text field contains the message body you entered.
mmcli output showing the contents of a received SMS, including number and text fields

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Create and send an SMS message from the device

Important: The destination must be a valid Hologram short or long code, not an arbitrary number. Use the number from the received SMS, visible in the number field of mmcli -s <index>.
1

Create the message in modem memory

sudo mmcli -m any --messaging-create-sms="number=+80112,text=g2-sms-reply-20260623"
2

Verify, send, and confirm

Verify the message was created, send it, then confirm it was sent:
mmcli -s 13
sudo mmcli -s 13 --send
mmcli -s 13
After sending, state changes from submit to sent and a message reference number is present.
mmcli output showing a created SMS transitioning from submit to sent state with a message reference

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Verify the message was received by the SIM

In your dashboard, open the Events tab for the SIM to view event history. You should see a new event tagged Outbound SMS (_SMS_DO_ event tag) with the message body matching what you sent.
Dashboard Event History showing an Outbound SMS event with the message body sent from the device

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Delete messages to free up modem memory (optional)

List the current messages: 
mmcli -m any --messaging-list-sms
Delete a specific message by its index: 
sudo mmcli -m any --messaging-delete-sms=7
mmcli output confirming an SMS was deleted from modem memory by index
To delete multiple messages in a loop: 
for i in 7 8 9 10 11 12 13; do
  sudo mmcli -m any --messaging-delete-sms=$i
done
Danger: Do not use mmcli -s <index> --delete. This syntax is broken in newer versions of ModemManager and returns error: no actions specified. Always use --messaging-delete-sms=<index> on the modem (-m) instead.