From: nisimura@sran233.sra.co.jp (Tohru Nishimura)
Subject: Subaddressing (was: ISDN/analog interfacing)
Organization: Software Research Associates, Inc., Japan
Date: Tue, 26 Jan 1993 11:49:37 GMT

jeff@is.s.u-tokyo.ac.jp (Jeff McAffer) write;

> I have seen some stuff on ISDN serial TAs which have analog ports on
> them.  If I want to dial *into* that analog port, how is that
> accomplished?  I assume that the analog port has some sort of
> subaddress but how do I specify that at the calling end?  Is the
> analog nature of the incoming call detected automatically by the TA?

In connection establishment phase, "type check" is done whether calling
equipment is allowed to connect equip(s) at called side. If same type
equipments (at least one) are there, all of them are "ringed."
Different type equipments are not able to talk each other, of cource.
For example, when you call an ISDN number with ordinal analog telephone
(with/without ISDN), and there is no voice equipemnt at called side, no
ringing occurs;  Synthesising (woman) voice would answer; "There is no
equipment you can talk with.....", even if "dataline" ISDN TA or ISDN/IP
card is attached at called side.  This is a Japanese implemetation. I
don't know other countries' implementation.

OK.  you would raise a second question; how to utilise subaddressing and
supplemental line numbers for one ISDN line, which can get multiple
equipments attached with only one line.

Subaddressing:
	With ISDN subaddres, you can distinguish equipments each other.
	From my knowledge, subaddress is user configurable arbitrary IA5
	(In early ISDN spec. BCD coding was used) string.  Unique subaddress
	can be assigned to each equipment ("port") and you can explicitly
	call one of them, for example;

		03-5276-7358#any_string_you_wish

	Oh well, if a subaddress is entered from ususal dial pad,
	subaddress is limited with [0-9].  I'm not sure red '*' and
	blue '#' keys are available for the case.

	Subaddressing has caveat.  Call from usual good-old-day's analog
	telephony system is not avail to specify a certain system with
	subaddressing.  For example, if you attach one answering machine
	and one G3 FAX machine at your home ISDN by means of ISDN (analog)
	TA cascading, non ISDN caller can not distinguish these two
	equipment.  If caller uses ISDN and calling equipments have ISDN
	functionality, type checking and equip selection are performed
	automatically.

Supplemental line numbers:
	To solve above mentioned caveat, additional supplement line number
	is assigned to one ISDN line.  In Japan, this is a optional service
	with some charge.  You must consult with ISDN provider and get one
	more number, and setup an ISDN TA with the supplemental number.

Any other question ?  It seems to be there ISDN professionals in this
newgroup, if I failed to provide correct information, please notify and
correct me.

About my ISDN (analog) TA;
The equip is very interesting because, it has no switch in front panel except
for power button.  This one is highly configurable, and all of operation are
performed with DTMF tone.  It also recognizes pluse dialing.  The only one
complain to it is, ahem, there is no way to reconform current setting.
Voice synthesis ?  If it was cheap personal answering machine, it would
have.

Tohru Nishimura
Software Research Associates, Inc Tokyo Japan
nisimura@sra.co.jp