presentationIndicator and Calling Party Number
ggf at LUCENT.COM
Wed Nov 3 11:23:39 EST 1999
I agree with you that H.225 is in error. The extension bit should be set
according to encoding rules in Q.931. In adding the support for octet 3a I
neglected to change the text for "Octet No. 3 Extension". This correction should
be a candidate for the implementor's guide.
The indicators in the ASN.1 were meant to cover the cases where the address is
not a telephone number that could go into a calling party number IE (or
connected party IE), for example any address of type AliasAddress.
henri.maenpaa at NOKIA.COM wrote:
> First, there seems to be some inconsistency about the use of 3a octet of
> Q931 CallingPartyNumber field in H.225.0. Hopefully this is just an
> editorial mistake.
> Q931 (05/98) states the following (chapter 4.5.1 Coding Rules):
> c) An octet group is formed by using some extension mechanism. The
> preferred extension mechanism is to extend an octet (N) through the next
> octet(s) (Na, Nb, etc.) by using bit 8 in each octet as an extension bit.
> The bit value "0" indicates that the octet continues through the next octet.
> The bit value "1" indicates that this octet is the last octet. If one octet
> (Nb) is present, also the preceding octets (N and Na) must be present.
> Whereas H.225.0v3 (09/99) seems to do the opposite in Calling Party Number
> field by telling to set the octet 3 extension bit to 1, and use octet 3a as
> "encoded following the values and rules of table 4-9/Q931."
> Second, I am also wondering why H.225.0 currently allows two methods for
> CLIP/CLIR indication:
> Octet 3a and the ASN.1 side presentationIndicator IE. OK, the standard
> states strictly that octet 3a overrides the other, and therefore there
> should not be insolvable conflicts at the receiving entity, but still why
> they were both included?
> -Henri Mäenpää, Nokia
Glen Freundlich ggf at lucent.com
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