When making use of VoIP (Voice over IP), careful consideration needs to me made as to how you would make a call to the emergency services if the VoIP service is not working.

What could stop VoIP from working?

The following are scenarios that could make your VoIP number from A&A not work:

Power cut in the local area - your internet connection and devices would lose power and not function
Fault with internet connection - could be caused by any number of reasons, an internet connection is dependant on a large number of things working, which could break and take some time to get fixed
A fault with your equipment - eg a router or telephone stops working for some reason
Fault with the ISP or the VoIP provider - Faults can happen.

The main thing

Ensure you have tested

Suggestions

...for a local power cut

In the past, a standard landline phone could be used to make calls as it would be powered from the exchange and still work if your premises had a power cut. With VoIP this is not the case.

We'd suggest the following as methods to make emergency calls during a power cut to you premises:

Use a mobile phone - ensure you have a mobile or two charged up and with a working service.
Have a UPS (Uninterruptible Power supply) which can power your internet equipment - router, phone, etc so that you have backup power to devices that will enable to you make calls. Test that this works!

...For faults with the internet connection or VoIP service

Use a mobile phone - ensure you have a mobile or two charged up and with a working service.

... for using 999 BSL - Emergency Video Relay Service

Access to 999BSL also requires an internet connection, the service provides an Android/iPhone app, so in the event of a problem with your internet connection using your mobile provider's data connection will give you access. More details at https://999bsl.co.uk/

...if you have poor mobile phone service

Without an internet service and without a mobile phone service extra planning would need to be done to ensure calling emergency services is possible.

Have a UPS (Uninterruptible Power supply) which can power your internet equipment - router, phone, etc so that you have backup power to devices that will enable to you make calls. Test that this works!
See if there is a public telephone box in the area, that works.
See if there are any local shops or petrol stations that would let you use their phone in an emergency - remembering not all shops are open 24 hours.

Other suggestions and help

ISPReview has a page about backup power options here: https://www.ispreview.co.uk/index.php/2021/12/solutions-for-battery-backup-of-fibre-broadband-and-voip-phone.html