H.450.x ASN.1 Modules

Markku Korpi korpim at SBS.DE
Sat Sep 20 14:08:19 EDT 1997

Pete and all,

two comments on this mail:
> It has been mentioned that when a gatekeeper performs a re-route it
> would be good for the client to know about it.  After much
> investigation, there seems to be no message in Q.931 that handles this
> case.  In the text that I proposed in Sunriver I suggested that a
> Facility message with a H.450 ctComplete should be sent.  However, this
> is not much use to an entity that does not support supplementary
> services.  Therefore it might be useful to add can extra case to the
> H323-UU-PDU to cover this, e.g.:
> {
>         h323-message-body   CHOICE
>         {
>                 setup                   Setup-UUIE,
>                 callProceeding          CallProceeding-UUIE,
>                 connect                 Connect-UUIE,
>                 alerting                Alerting-UUIE,
>                 userInformation UI-UUIE,
>                 releaseComplete ReleaseComplete-UUIE,
>                 facility                Facility-UUIE,
>                 ...,
>                 progress                Progress-UUIE,
>                 dummy                   NULL,


I must have missed the "dummy" parameter before.  I assume the need for
an empty parameter comes from supplementary services, and I suggest to call
it "empty NULL" (this is not an implementation but a standard after all)
and to describe it somewhere in H.225.0.  Searching through the document,
the ASN.1 was the only place where "dummy" was used.
(Should I be saying something about puzzles right now? :-)
>                 reRouteIndication       ReRouteIndication
>         },
>         nonStandardData NonStandardParameter OPTIONAL,
>         ...,
> h4501SupplementaryService       SEQUENCE OF H4501SupplementaryService
> }
> ReRouteIndication ::= SEQUENCE
> {
>         display         IA5String (SIZE( 0..255) ),
>         endpointInfo    EndpointType,
>         ...
> }
> This could then be sent by a gatekeeper when a re-route has been done.


Overall, I agree with the mail from Ernst Horvath on this issue: we should
not add such functionality to H.225.0, not even to version two.


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