While everything is normal, the tills talk to Softphia through your router, and the SoftEdge phone only stands by: it checks the shop’s internet and reports to Softphia every 30 seconds that it is ready.
When the internet fails, each till notices that Softphia no longer answers and, within seconds, sends its traffic to the phone instead. The phone passes it on over mobile data. A slim line at the top of SoftPOS and SoftKitchen shows that the backup line is in use. Sales, kitchen tickets, receipts and card payments continue; printers and card terminals stay on the local network as before.
When the internet is back and stable, the tills return to the direct line by themselves, about a minute later, and the line at the top disappears. SoftEdge stays ready for the next outage.
A drill in the SoftEdge app sends a real request through the backup line, so you can check that everything works before you ever need it.