I'd read last years messages about this matter, and just today I got a call offering massive discounts on my telephone bills.
The 'heavy Asian' voice (no disresepct intended) definitely said "Spirit Telecom" as I had him repeat the name a couple of times.
I'm a TelstraClear customer, but he didn't seem to realise this, and just spouted a heap of call 'data' that could be from any normal home in NZ.
As advised, I simply firmly said "No thanks" and hung up.
R.