Adding remote power cycle / reboot capabilities to an isolated home assistant system without people with an SMS gateway

I have some RPI’s that are remote, and it takes days to get humans to the location.
In the last 5 years I had to reboot the whole stack 3 times, so here’s the automation setup to reboot it all remotely with an SMS (asuming the home assistant is up 🙂

Add https://github.com/PavelVe/home-assistant-addons to your addon’s (or whatever)

Have MQTT set up on your HA

optional: add an sms gateway user / pwd

Install & configure the SMS addon, throw in your newly created credentials

start up the gateway

it should show up

Activating the Orange simcard

 Activating an Orange Mobicarte SIM via AT Commands on a SIM800C
                                                                                                                                                                                                                                                 
  Context                                                         
                                                                                                                                                                                                                                                 
  I had a SIM800C GSM modem connected to a Home Assistant instance via a CH340 USB-to-serial adapter (/dev/ttyUSB0). The SMS Gammu Gateway addon was failing to send SMS with Gammu Error Code 27, which translates to +CMS ERROR: 69 ("Requested
   facility not subscribed") at the AT command level.

  Before debugging, I stopped the SMS gateway addon to free the serial port:

  ha addons stop 06c5e726_sms_gammu_gateway

  Serial port setup

  All commands use the same setup — configure the serial port and open a file descriptor:

  stty -F /dev/ttyUSB0 9600 cs8 -cstopb -parenb -echo raw
  exec 3<>/dev/ttyUSB0

  Calling 225 to activate the SIM

  Orange France requires you to call 225 to activate a Mobicarte and receive your phone number via SMS.

  # Dial 225 as a voice call (the semicolon makes it a voice call)
  echo -ne "ATD225;\r" >&3

  Response:
  OK

  After ~30 seconds the call ends:
  NO CARRIER

  Hang up cleanly:
  echo -ne "ATH\r" >&3

  Reading the received SMS

  First, switch to text mode and set SMS storage to SIM card:

  echo -ne "AT+CMGF=1\r" >&3        # Text mode
  echo -ne "AT+CSCS=\"GSM\"\r" >&3   # GSM charset
  echo -ne "AT+CPMS=\"SM\",\"SM\",\"SM\"\r" >&3  # Use SIM storage

  Then list all messages:

  echo -ne "AT+CMGL=\"ALL\"\r" >&3

  Response (4-part concatenated SMS from Orange):

  Orange : Votre numéro mobicarte est le +33XXXXXXXXX. Conditions de l'offre sur https://r.orange.fr/r/Srcmobi . Vous pouvez recharger votre compte dans les boutiques orange, boutique.orange.fr ou travel.orange.com

  Bonus: Checking prepaid balance via USSD

  echo -ne "AT+CUSD=1,\"#123#\"\r" >&3

  Response:
  Accueil
  Crédit rechargé: épuisé
  Validité de la ligne: 24/08

  "épuisé" = exhausted — the SIM had zero credit, which was the root cause of the SMS send failures.

  Summary

  ┌────────────────────────┬────────────────────────────────────┐
  │       AT Command       │              Purpose               │
  ├────────────────────────┼────────────────────────────────────┤
  │ ATD225;                │ Voice call to 225 (SIM activation) │
  ├────────────────────────┼────────────────────────────────────┤
  │ ATH                    │ Hang up                            │
  ├────────────────────────┼────────────────────────────────────┤
  │ AT+CMGF=1              │ Switch to SMS text mode            │
  ├────────────────────────┼────────────────────────────────────┤
  │ AT+CPMS="SM","SM","SM" │ Set storage to SIM card            │
  ├────────────────────────┼────────────────────────────────────┤
  │ AT+CMGL="ALL"          │ List all SMS messages              │
  ├────────────────────────┼────────────────────────────────────┤
  │ AT+CMGR=N              │ Read message N                     │
  ├────────────────────────┼────────────────────────────────────┤
  │ AT+CUSD=1,"#123#"      │ USSD balance check                 │
  └────────────────────────┴────────────────────────────────────┘

 

adding the shell command.
I have NUT running so claude came up with this NC command to reboot the UPS

(I initally had a simple docker exec, but docker isn’t a recognised command)

shell_command:
  powercyle_ups: docker exec addon_a0d7b954_nut upscmd -u nut -p beepboop APC shutdown.reboot

shell_command:
  powercycle_ups: 'printf "USERNAME nut\nPASSWORD beepboop\nINSTCMD APC shutdown.reboot\nLOGOUT\n" | nc -w 3 a0d7b954-nut 3493'
  

for the automation part, I have an allow list of phone numbers who can text reboot

alias: "[SMS] Reboot Cabinet"
description: Power cycle server cabinet via UPS when SMS reboot command is received
triggers:
  - entity_id: sensor.sms_gateway_last_sms_received
    trigger: state
conditions:
  - condition: and
    conditions:
      - condition: template
        value_template: "{{ trigger.to_state.state | lower | trim == \"reboot\" }}"
      - condition: template
        value_template: >-
          {{ state_attr("sensor.sms_gateway_last_sms_received", "Number") in
          ["+3200000000", "+3200000001", "+3200000002"] }}
actions:
  - action: shell_command.powercycle_ups
    data: {}
mode: single