No. The official report seems to suggest that software in IMS core (the subsystem that controls VOIP signalling in the mobile network) bugged out after the time was shifted back 20 years. That doesn't narrow down the specific failure that stopped calls from going through very much. IMS core is full of timers, but it could also have been a license server issue for all the report said about it.
I haven’t read the report, but I did read at the time that it was a certificate validation failure: clients thought the current time was before the "Not Valid Before" date. I forget now what essential service became unavailable because it was disbelieved.
(Source would either have been the Whirlpool forums – where Australian ISP and telco engineers can be found – or local Australian mass media.)
That's also plausible.