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From: fgoldstein@bbn.|nospam.|com (Fred R. Goldstein)
Newsgroups: comp.dcom.isdn
Subject: Re: Yet Another : Whats SPIDs
Date: 29 May 1997 21:21:20 GMT

In article <>, says...

>Understanding SPID's
>What do they do ? And why do you need them ?

They annoy people.  To annoy people.  Basically, to provide telco CO people 
total control over Centrex telephone sets, and anything else that barges onto 
their Centrex-ISDN switch.  (Bells hate ISDN without Centrex.)

>SPIDs are constructed (normally) from the phone numbers
>and include (at begining/end ?) something like 4 digits
>(is this a fixed number of digits ?) that was once meant to
>cary some meaningfull information (if you know what the
>positional values means), but some switch types does'nt seem
>to care about them, eg. some ISDN users reports that there is
>no diff. in functionality no matter what they set them to.

Typically 10-digit DN+4 digits, but "AT&T Custom" was a different
format, and the last two digits are really the TID and often don't

>Since SPID's apparantly always involve the phonenumber, i wonder if
>SPID's are different if you have several (not 2, but maybe 8 phonenumbers
>on the same BRI)

DN and SPID are different.  Read on.

>Are SPID's just descriptions of individual B-Channels ?
>That is, is it something like En-/Disable DATA, Audio, 3.1 Khz
>Audio and ? or are they ment to cary other/more complex meaning.
>Does a "complex" setup require more than 2 SPID's

A SPID is a "profile" of the options, keyset button layout, feature button 
layout, DNs, etc., assigned to an ISDN TE.  There is supposed to be one SPID 
per TE; however, NI-1 follows the NorTel abomination and assigns one per 
active B channel.

You probably understand what a TEI is at layer 2.  A SPID corresponds to the 
TEI, but lives at layer 3.  A TE initializes layer 2, then Registers its 
SPID, then can use layer 3.  The 1:1 mapping even extneds to the NorTel 
abomination:  Each B channel not only has a separate SPID, but a separate 
TEI!  So for instance my ISDN router has two active TEIs, each corresponding 
to a SPID.

If you have a bus with multiple devices, each device has a unique SPID or 
two.  NorTel only handles up to 2 B-channel-capable SPIDs per BRI; Lucent and 
just about everybody else handles up to 8.  In theory, two *identical* 
devices sharing a line (say, two keysets) can share the (12-digit) SPID, but 
differ only in the TID (last two digits).  Not that I've ever seen it done.

>Example (my setup)
>ISDN card attached to a NT. The card is hybrid, meaning it can
>carry 1 Analog connection (V.34, V.FC, FAX etc.) and 1 digital
>connection (X.75, HDLC *, V.120). Offcourse it can also carry
>two digital connections.
>I use 1 driver that delivers a bunch of COM ports on the (OS/2)
>I configure it kind a like this
>Port         PhoneNr  BC            Application
>COM3         -121     DATA & AUDIO  BBS
>COM4         -121     DATA & AUDIO  BBS
>COM5         -122     DATA          UUCP
>COM6         -122     AUDIO         FAX
>COM7         -123     DATA          Remote Control Soft
>COM8         -124     DATA & AUDIO  PPP router
>etc. etc. etc.

>I use another app. for capi that listens to my voice phone
>number and acts as an answering machine, it also listens
>to -123 Audio, and tells people that this is a Data only

>Now comes the big question ! Does a setup like the one described
>require any modification w. respect to SPID's

It is still only one or two SPIDs, since it's one card.  DNs are separate.  
You can stick as many DNs as you want on a SPID -- we do have MSN as well as 
DDI (which we call DID).  I don't have that on my line, for instance, so I 
only have two DNs, one per SPID, but if I wanted to pay for MSN (I think 
NYNEX wants a dollar a month per number) I could get it.

>I have previously gotten response from people who "defined" that
>SPID's where needed to differentiate two seperate ISDN phones
>(like : Mine and my wifes phone) If they where not, the Speed
>Dialling buttons would'nt work (would be identical).

>Now i might not be good enough at english, but i translate
>"speed dialling button" into something like "Press Memmory button,
>Press a two digit sequence and the phone will dial a previously
>stored number"

>If this is true, the above statement would indicate that
>the speed dial mappings where stored at the CO/Switch
>Is this the case at any american CO/Switch, be it PSTN, ISDN
>or both ?

Yes, that's the way it works.  An ISDN phone would typically have 
dumb buttons that use stimulus Feature Activator messages to inform
the switch that they've been pressed, and the switch stores the speed
numbers.  Of course we have phones with built-in memory, but that's
not the way Bells want Centrex to work.  ("We control the horizontal,
we control the vertical.")  Likewise we do NOT program our ISDN devices
to know what they respond to; rather, the switch does it for us, and
the devices are dumb.  Not that this is better, but it allows Centrex
systems be installed with one trained technician at the remote NOC someplace 
entering all the feature translations, while untrained gorillas install the 
actual telephone sets.  Also note that in the US, Centrex includes LINES 
only; the telephone sets are installed by somebody else, owned by the 
subscriber, so telco would lose CONTROL if the (correct) European/ITU model 
were followed.

>To summarize :

>What should the SPID's indicate ?

It's really a password.

>Can you have more than 2 SPID's in any given TA ?

In general, it would not be rational.

>Should 2 ISDN phones configured for the _same_ phone
>number have the same SPID ?

No, though it's possible, in theory, that they differ only in the TID, but 
that's usually entered as the last two digits of the SPID.

>and above all... WHY do you need them ? There must be some
>reason for them to exist !

Centrex.  And because Bell companies hate ISDN.  And because NorTel and 
(then) AT&T Technologies wanted to implement them, and they didn't need no 
stinkin' standards.
Fred R. Goldstein   k1io    fgoldstein"at"
BBN Corp., Cambridge MA  USA         +1 617 873 3850
Opinions are mine alone; sharing requires permission.

From: fgoldstein@bbn.NO$ (Fred R. Goldstein)
Newsgroups: comp.dcom.isdn
Subject: Re: ISDN, SPIDS and Area Code Splits
Date: 11 Sep 1997 21:13:08 GMT

In article <>, says...

>What is likely to happen is that at some (unannounced) time in
>the future, your friendly telephone service provider will
>change all the SPID's (or maybe even just some of them, don't
>ask for consistency) on the switch to match the new area code.
>There's every chance that the phone company will make *no*
>effort to coordinate the change with customers, so all customer
>equipment will mysteriously stop working, and be out of service
>for a day or two -- or whatever.

Bingo.  That happened in Chicago during the 847 split, and Ameritech's a darn
site more positive about ISDN than BTi!  One day your SPID will change,
unannounced.  This should occur during the permissive period.  Don't ask
when, they probably won't tell.  They probably don't know.  If you are
already on line (D-channel up) it'll stay up, but next time you initialize
the TE, it'll fail, and you'll need to change the SPID.
Fred R. Goldstein   k1io    fgoldstein"at"
GTE Internetworking - BBN Technologies, Cambridge MA USA  +1 617 873 3850
Opinions are mine alone; sharing requires permission.

Newsgroups: comp.dcom.isdn
From: fgoldstein@bbn.NO$ (Fred R. Goldstein)
Date: Tue, 30 Dec 1997 15:04:08 GMT

In article <>, says...

>I recently was told that it is possible to have the same SPID on both B
>channels, and to have both B channels set up for both voice and data.
>Can anyone confirm this?  And if so, how can I get my local service
>provider (Bell Atlantic North) to understand how to provision my service
>this way?

This is a little confusing.  "SPID" was originally *supposed* to be an
identifier for the terminal device itself, so you could plug in, say, a
phone, a fax, and a computer into one BRI (up to 8 devices), and each would
have different feature sets, identified by SPID.  Trouble is, NorTel
implemented it wrong, defining the two B channels of a BRI as separate
virtual TEs, each with its own SPID.  Furthermore, they limited a BRI to two
(circuit-capable) SPIDs.  So NorTel's implementation in effect lowered the
bar from eight devices to one two-channel device.

AT&T (now Lucent) did the 5E a little better.  On its "Custom Point-to-Point"
option, which can probably still be cajoled out of Bell Titanic - North, you
have NO SPID, so it's really easy to set up.  However, it only allows one
simultaneous voice call, which is rather limiting with the need for DOV here.
"AT&T Custom Point-to-Multipoint" uses SPIDs, but theoretically allows one
SPID per device, with two B channels on that SPID.  In practice, it is often
set up with two SPIDs.

National ISDN-1, Bellcore's 1990 abomination which became sort of the
standard, is based on NorTel.  So it's *allowable* to limit devices to one B
channel per SPID.  That's what the DMS does, and how it's usually provisioned
on the 5E (for consistency; the 5E is actually smarter).

More important is the way "voice" and "data" privs are provisioned.  On a
NorTel DMS, a line is provisioned for "circuit" (0/1/2 channels).  You can't
provision it for voice only or data only.  The 5E has separate voice and data
bearer limits per SPID.  When NYNEX wrote the tariffs, they didn't know about
the DMS limits.  So they charge $5/month to data-enable a B channel, nothing
(above your call plan) to voice-enable it.

Since "data over voice" is the norm anyway (which drives them deservedly
crazy), you really want "2 voice 0 data".  As another thread discussed this
past weekend, it's rather hard to order that, in MA at least.  (It's okay in
NYC, where an untimed second voice B channel carries a $7 charge, vs. $0 in
MA.)  The tariff doesn't explictly prohibit it though.  It's easy to order "1
voice - 1 alternate voice/data (AVD)" which, for $5 (to enable the data),
lets you make two simultaneous voice calls.  You typically get two SPIDs,
though you might be able to find somebody to set it up with one if it's on a

On a DMS, you can order 1 voice 1 data and get, in effect, 2 "AVD".  Heck, "2
voice" will give you 2 AVD on a DMS, if you can get it past Telemon
(1-800-[for]GET-ISDN).  This is small consolation given the other weaknesses
of the DMS.  (However, the DMS will be made whole two releases from now.
This statement is always true, as it has been for four years.)
Fred R. Goldstein   k1io    fgoldstein"at"
GTE Internetworking - BBN Technologies, Cambridge MA USA  +1 617 873 3850
Opinions are mine alone; sharing requires permission.

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