However, the phone system is almost completely useless. He has two phones
in his office and cannot call one from the other. (Although he says they
are on different exchanges, so they might not hit the same CO.) Dial tone
is there, but after dialing numbers, just dead air. Which is weird,
because when I called him it rang and he picked up, no static or
anything. (We do have a switch in NZ, but we have to ride the local PTT to
the destination phone.)
There was documented overloading in international calls in and out of
New Zealand through CLEAR, Telecom NZ, Telstra NZ, Vodafone and Voyager.
There was difficulty in seizing a line on Vodafone and Telecom NZ
cell sites around central Auckland just after midnight, which is somewhat
understandable considering there were several hundred thousand more
potential cellphone subscribers in the area than is normal for a Friday
night.
There was, however, no widespread difficulty measured within NZ in
obtaining dial tone, switching calls between local exchanges and
tandems, or in interconnect between the main carriers.
This is causing unusual failure modes for some systems, especially ISDN
routers which are common in .nz and .au.
ISDN routers are mainly only used in NZ where the calling and called
station are attached to the same exchange, as this allows both stations
to be combined in a centrex private dialling plan, which is billed on
a flat-rate. Non-centrex ISDN is typically not used for nailed-up
services here, since they incur a substantial per-minute charge from
Telecom. Basic-rate services are available from other carriers, but
Telecom is the only carrier with a widely-available copper access
network.
So although instability in a local exchange might give ISDN routers
some connectivity problems, congestion on tandem trunks would be
unlikely to impact them at all, at least, without roll-on instability
problems. I believe Telecom NZ do use in-band R2 signalling from LXes
which has been known to cause high LX processing load during periods of
attack dialling, however, so it's possible that in individual cases ISDN
centrex services might be affected.
But again, no long-lasting or widespread problems have been reported.
So, overall, I would say that the world is probably not going to end. 
It's still here as far as I can see. Mind you, I haven't been outside
yet today
Important lesson, I think, is to understand that individual isolated
problems reported by individual operators do not necessarily signal the
collapse of the PSTN.
"The phone system is almost useless" is perhaps less accurate than
"the one person I have talked to has reported some problems with his
office handsets"
Joe
