[aaronmdjones]

If the OS doesn't recognise it as an emergency number then it may fail the call if it believes that whatever network it is associated with won't connect it ("No service" vs "Emergency calls only" indicators etc if you are out of coverage from your SIM's network but within range of other networks).

Emergency calling is supposed to work over any network (even without a SIM card inserted, much less an activated, registered, associated one), but only if the OS tries to dial it as an emergency call.

[johann8384]

But this wasn't a new emergency number.

[dundarious]

It's not about the "age" of the number at all, devices are mandated to try all available networks when it is a recognized emergency number. In this case, even though the number was indeed a device-recognized emergency number, it failed to try all available networks as mandated. The article mentions Triple Zero several times, but not because that is specifically noteworthy beyond it being the typical emergency number.