how to send a Display message via CAPI driver?

[Juergen]

Hello,

I am new to this group and not very experienced with ISDN programming. We use
the Delphi DLLs from Cytel to program an ISDN-application.

Now we have the requirement to send some text-info to the display of a called
ISDN-phone (which can handle and show that "Display" message) connected
internally to the pbx. No need to send this via a public network. It should be
displayed while the called phone rings (before phone is picked up).

I have read a lot now about UUS1-data and Display Info-element and had a look
through the ETS 300 102-1 and Q.931 ... and am more confused than before.

An example D-channel trace with such Display-data sent from the pbx to an
ISDN-phone (which has then shown "22" on its display):

01.12.07 13:07:08.45 >I 02 83 02 04 08 01 14 7B 28 02 32 32
INFORMATION TEI=83 CallRef=14
DISPLAY 22

My question now is: how can we send such a message to a phones display from
our application via the CAPI-driver/ISDN-card? I understand the part from
... 28 02 32 32, that is: 0x28 for Display info-element, 0x02 for len 2 and
then the "22" (data to display). What I do not understand is the format and
content of the 8 bytes before that part (the: 02 83 02 04 08 01 14 7B).

What we tried (with the help of the developer of Cytels ISDN toolbook) is:
they modified their UUS1 function (called during setup/init for a new
connection / Dial out) but that did not work out as expected, the result was:

01.12.07 13:07:08.35 >UI 02 FF 03 08 01 14 05 A1 04 03 80 90 A3 18 01 8A
6C 04 41 80 32 32 70 03 81 32 35 7D 02 91 81 7E
10 28 0E 42 69 74 74 65 20 4B 61 66 66 65 65 20
6B
SETUP TEI=FF CallRef=14
Bearer speech
B-Channel 02
Calling Party 22
Subscriber number
ISDN/Telephony numbering plan
user provided, not screened
presentation allowed
Called Party 25
unknown type
ISDN/Telephony numbering plan
HLC Telephony
UUS1 unknown 0E 42 69 74 74 65 20 4B 61 66 66 65 65 20 6B

So I assume, that they used their UUS1 functionality (because I see the
7E 10 ...) and passed
28 0E 42 69 74 74 65 20 4B 61 66 66 65 65 20 6B as UUS data
(28=Display info-element, 0E length, 42 ... 6B = display text).
Of course, that can not work as expected since it is interpreted as
UUS data (7E) and not as Display data (28).

Now at this moment it seems, they do not know how to proceed / solve this
requirement of sending Display-data INSTEAD of and not as PART of UUS1-data.

Does anyone in this group has experience with the Display info element and
could kindly help me in this regard (explain how the 8 bytes before the
28 02 32 32 need to be formated and set to get a text displayed on the
target phone)?

Wbr,

Juergen

[Christoph Schweers]

Hi Juergen,

the aim of the Information Element DISPLAY is to display Network related
infos to the user. Therefore it is always send from the network to the
user. If you look to your 102-1 you always will see something like this
"n -> u" ;-)

If you want to send an information from one user to another you have to
use the so called "User-to-User" signaling. But this isn't covered by
the basic call control defined in ETS 300 102. Therefore you should take
closer look at ETSI ETS 300 286.

Regards
Christoph

[Juergen]

Christoph,

thanks a lot for your answer. It was very helpful for me to understand
(parts of) the story.

We can comm. in German, isnt it? If not --> see the engl. text below.

----------------------------------------------------------------------
German:

das hab ich, glaub ich, verstanden. display-info (n -> u) kann nicht
von der isdn-card via capi gesendet, sondern nur empfangen werden, oder?

die en_30028601v010204p.pdf hab ich mir angesehen. werd aber auch nicht
viel schlauer daraus (Display ist dort nur im Zusammenhang mit
CONGESTION CONTROL erwaehnt).

also geht fuer unsere anforderung nur UUS(1)? Aber koennen wir da auch
gezielt auf das Display zB. eines an der pbx angeschlossenen Dect-Phones
schreiben? Da hab ich auch in der ETS 300 286 nix gefunden ausser
"CONGESTION CONTROL" mit dem Display-element, die koennen wir aber fuer
unsere Zwecke nicht nutzen, oder?

Danke fuer Deine Hilfestellung!

Juergen

----------------------------------------------------------------------
English:

I uderstood (I hope): display info (n --> u) can not be sent via
ISDN-card/capi, but only received, isnt it?

I have reviewed en_30028601v010204p.pdf - it did not enlight me either
with an ultimate solution ... ;-)

So, for our requirement, we could only use UUS(1)? But can we, then,
send and display some text to i.e. a Dect-phone (connected to the pbx)
display? UUS is proprietary, isnt it? And has no explicit
Dispay-fctn.?

UUS is (network) transparent user-data as I understood. And will,
therefore, not be displayed on the target phones display but just be
passed through by the network to be interpreted by the end-device
(and dropped, if unrecognised)?

But then, how to get our text displayed on the target Dect-phone locally
(not over any providers network)?

Thanks again for your help,

Juergen

Post by Christoph Schweers
Hi Juergen,
the aim of the Information Element DISPLAY is to display Network related
infos to the user. Therefore it is always send from the network to the
user. If you look to your 102-1 you always will see something like this
"n -> u" ;-)
If you want to send an information from one user to another you have to
use the so called "User-to-User" signaling. But this isn't covered by
the basic call control defined in ETS 300 102. Therefore you should take
closer look at ETSI ETS 300 286.
Regards
Christoph

[Mario Goegel]

Hu Juergen,

sorry, i can't you explain these 8 bytes, but before you can think about
that, you have to meet the requirement:

a) the phone is attached to an NT configured ISDN card (network master)

or

b) You need a PBX wich understands QSIG-GF (Generic Functions) and have
a ISDN card, which can do QSIG.

In the last case, you could send a calling name and the PBX has to send
it in the display IE. The encoding of this facility isn't too hard.

Mario