I sked Voipfone what caused the outage and got this response:
"I don't have the details regarding the outage but believe it was out of our control and a full incident report will be published as soon as it's completed. "
My gripe was really with Voipfone was that their
https://www.voipfonestatus.co.uk/ web page failed to acknowledge there was any problems with their network at all, proudly proclaiming a 100% uptime when clearly this was not the case. A day after the event, all their status page had to say was "Network availability. This incident has been resolved. Aug 26, 16:54 - 20:06 BST" - No apology for inconvenience caused and no detail of what went wrong and even worse was that their status page still claimed for the day in question that uptime was 100%!
I feel subscribers are entitled to know comprehensively when there is a problem with any network, with some kind of indication when the service might be restored and not to be mislead on their status page that everything is OK. Otherwise status pages are quite pointless.