How to, user set up- list of cellular numbers for sms?

I am playing around with a temperature network using Wifi Nodes and looking at Node-Red or Domoticz as the main controller (MQTT).

One of the issues I come up with is how to provide a means for the end user to enter a list of cellular numbers to send SMS alarm message in event of an alarm. If the end users always had internet connection via a wifi AP then this would not be an issue but in most cases the users will not have internet access, the network will run local and independent of the net. I also need users to be able to send sms request to the system to get report of current status.

I could add an external touch screen device but as the controllers offer url based viewing of the data, it seems a bit inefficient to add reasonably expensive hardware just for the phone list.

I am not that literate in writing scripts to create an http based form and figuring out how to save it and then use the form to send the SMS to each number in turn during an event.

Would it be better to have the alarm sent to the Hologram dashboard and then some sort of webhook to an SMS service that the customer could log into to manage the phone list?

Initially, I was going to use the Huawei 3G USB modem but maybe would be better to use the new Hologram Nova?