An old-fashioned analogue telephone on a copper line doesn't need electricity. If plugged straight into your line, it works fine through a power-cut.
But a phone on a UFB fibre and fixed-wireless internet connection - that is, what most of us use today - requires a modem to connect it to the internet for calling, and that modem requires power (fixed-wireless is when a mobile phone network is used to deliver broadband to a home or business).
The new code says to consumers: get a mobile phone you can use to make emergency calls instead, or install an uninterruptable power supply (UPS). Since a decent UPS costs hundreds, it can be tricky to set up and might only last a fraction of the length of a power cut, a cheap mobile phone on pre-pay is your best bet, if you don't have a mobile. A basic "burner" (a cheap mobile phone, usually used by crims or mayors having affairs as a disposable) will cost as little as $40. Emergency calls are free.
If you have poor or no mobile coverage, or poor mobile coverage, then your phone company has to help you out with a UPS or other solution.
That brings us to telcos' obligations under the new code.
That is, service providers must tell new customers, and remind existing customers at least once a year, that their home phone may not work in a power cut. Providers must also tell their customers how they can protect themselves and where to go for further support.
Home phone customers who don't have an alternative way to contact 111 in a power cut can apply to their provider if they are at particular risk of needing to call emergency services for health, security or disability reasons. If they qualify, their provider will work with them to determine the right product for their particular needs, at no cost to the consumer.
The code comes into effect in February next year, though providers have until August 2021 to make the process for extra support available to vulnerable consumers.
If your phone company doesn't follow the code, you can complain to the Telecommunications Disputes Resolution Service, which provides a free, independent resolution service.
The emergency calling problem has taken on a sense of urgency for Spark. Customers in Devonport and Mirimar have been told to upgrade from copper lines to fibre or fixed-wireless fixed by December 18 - or switch to another provider.
Other areas could follow this "forced march" if the pilot is successful. (While new legislation, being phased in between January 2020 and 2022, will give Chorus the right to pull out copper in areas where UFB fibre and/or fixed wireless is offered, the network operator said last week that it was not about to do so anywhere and that it would complain to the ComCom about consumers being rushed, in its view.)
Beyond emergency calling, the move from copper to fibre or fixed-wireless could cause problems for some security or medical alarms.
Spark says all customers who move off copper will be offered a cheaper plan, and that it has tested affected equipment.
A spokeswoman said: "Spark has tested a number of special devices to check that they work on the wireless network, although there may be many others we are not aware of. For this reason, we won't be moving customers with any type of special device across until we can make sure there is a wholly appropriate solution available."
POSTSCRIPT: In an emergency, should I phone 111 or 112?
After a recent debate in the geek community over whether it's best to call 111 or 112 from your cellphone in an emergency, Police posted a notice encouraging people to dial 111.
112 is an international emergency number that works in almost every country, including NZ (where a 112 call will be automatically rerouted to 111).
It's not correct that 112 will give you an inside edge getting through. When you dial 111 on your mobile, your phone will also try to reach any available network (that is, if you're a Vodafone customer, it will also try to reach a Spark or 2degrees tower if necessary).
Still, 112 is handy to remember when your travelling, since it works everywhere, and emergency numbers differ (the US is 911 and Australia 000, for example).
In an emergency, it can be better to send a text than attempt a voice call. A text is easier for any mobile network to handle, and if there's overloading, Vodafone, Spark and 2degrees' systems will all automatically keep trying to deliver a text until things clear up.
One final point: in Australia, there's an additional emergency number, 106, which the hearing or speech-impaired can text in an emergency.
Here, you can text 111, but only if you've registered your number.