Reacting to Telegram Message that are sent from a bot in a group chat

Hello everyone,

I’m trying to trigger a Home Assistant automation in our fire station whenever an alarm comes in.
The alarm is received on my phone via aPager. Since I can’t access the alarm directly inside the fire station, I’m using a workaround:

aPager runs on my phone and sends a Telegram message to a bot. Home Assistant is then supposed to read that message and trigger an automation.

So far, the first part works:
• aPager successfully sends the Telegram message.
• The message is actually delivered.

The problem is:
• Home Assistant does not react to the messages sent by the bot.

What I have already checked:
• The Telegram bot is set up in Home Assistant.
• The message is sent from the phone.
• The bot seems to receive the message.
• Still, no trigger is fired in Home Assistant.

I suspect the issue is related to the Telegram integration or the trigger configuration.
My goal is simply to use a specific Telegram message as a trigger for a Home Assistant automation.
Has anyone done something similar successfully or has a tip on what I should check?
Do I need a special polling trigger, an event trigger, or a certain Home Assistant configuration for this to work?

Thanks in advance for any help!

With this code HA reacts to message I send to the bot. So I know the bot etc. is set up correct.

alias: Telegram Gruppe Alarm
triggers:
  - trigger: event
    event_type: telegram_text
actions:
  - data:
      message: pong
    action: telegram_bot.send_message

With this command the alarm app for the firefighters sends a message into my Telegram Chat.

(https://api.telegram.org/bot14xxxxx:xxxxx/sendMessage?chat_id=12860xxxx&text=Alarm)

When sending any text (see right side of the picture) HA sens a Pong respones in another chat. But when FeuerwehrAlarm sends a message nothing happens.