Just days ahead of the shutdown, Australia's media regulator ACMA finalised a new "direction" (basically a rule) that meant telecom companies had to refuse service to all phones that relied on 3G for making emergency calls.

The idea was to prevent people from mistakenly believing that phones were fully working, only to realise they were unable to make emergency calls when the crucial moment came.

Australians with older 4G phones may also be caught out because of the way the phones are configured.

It is up to the telcos to work out which phones are affected, notify the owners, block their phones, and help make other arrangements such as low- or no-cost replacement phones.

However, as Telstra and Optus noted during a Senate inquiry into the shutdown, telecom companies are unable to tell which individual devices suffer from this problem unless have they sold them.

I'm not saying it's not partly on the providers, but validating that a bunch of obscure phones that aren't sold in your country meet new regulatory requirements is not as easy as you're making it out to be.