Gsm doorbell calling house phone

Sorry need help. Wife is disabled and cannot get to door easily. Tried ring type doorbell but useless.
I think An arduino with gsm hat would call house phone then mobile when doorbell pushed and could speak to person. I don't know where to start. Any help would be good. Thankyou

Where I live, all the lobby buzzers in the high rise apartments, go to a phone number. The occupant might hear a bell or receive a text, I'm not sure, but after that, they can speak to the visitor in the lobby on their cell phone. You might want to investigate this off the shelf solution.

You could google for : “gsm based door intercom” to get an idea of what features you would like to implement e.g. unlock main entrance door. You’d also have to think what would happen if the house phone was already in use at the time the visitor called.

You can also look here for a building block for making cell phone applications: Overview | Arduin-o-Phone | Adafruit Learning System

and see some commercially available systems here to get an idea of what features to implement: Wireless Intercom System Review for 2021 by Intercom Experts

@beatbunty, as this is not related to Covid19, your topic has been moved to a more suitable location on the forum.

Do you have decent wifi coverage in the house door areas, and her rest/living areas?

That approach may well be cheaper to run than a SIM plan, or alternately a simple 433MHz wireless link to fixed or portable ‘alert’ units as needed.

There’s a few good ways to achieve this, not the least being an off the shelf RING style of device.