Simon;
Voice over IP is paradoxically both internet and telephony at the same
time. This article presents the paradox, and associated arguments.
There is no paradox. The internet carries information.
You should, at least, distinguish VoIP as a telephone network
and the Internet telephony.
There is no "internet telephony"...
See my paper "Simple Internet Phone" presented at INET2000.
http://www.isoc.org/inet2000/cdproceedings/4a/4a_3.htm
It, for example, says:
However, it is obvious that the telephone network will be
replaced by the Internet, and will eventually disappear.
there is "IP telephony" which is
There is no "internet telephony"... there is "IP telephony" which is
not running on the public internet. There is also VoIP on the public
internet which I like to call "Voice Chat".
Apparently, you don't recognize the current situation, which I
foresaw several years ago.
Voice chat, of course, is no internet telephony.
Paradoxical reguration on voice in US is a US local issue.
Please cite a document, I don't find any japanese regulation that makes
it any different there...
Japanese telecommunication laws (available at
http://law.e-gov.go.jp/cgi-bin/idxsearch.cgi) does not distinguish
telephony or voice something special and the requirement on
providers is same, though detailed requirements varies.
In Japan, TAs to connect the Internet and POTS telephone devices
are rapidly replacing the telephone network including VoIP ones.
... do they provide PSTN-level availability?
In theory, yes.
In practice, there is no such thing as PSTN-level availability.
in an emergency / power
failure?
In emergency, best effort network works better than circuit
swithced one, of course.
As for power, have you ever used ISDN with TAs?
Masataka Ohta