Subject: [Sipping] ISUP draft: Issue on cause code mapping

From: "Drage, Keith (Keith)" <[email-masked]>
Date: Wed, 12 Dec 2001 16:40:18 -0000

In draft-ietf-sipping-isup-00.txt when ISUP cause codes are mapped to
status-codes, no account is made of the location field.

This is particularly critical in the area of busy.

Cause code #17 covers only user determined user busy (defined somewhere in
the ITU-T I.220 series).

Cause value #34 has a number of uses. When it is used by an exchange
supporting a user access to which the cause refers (i.e. remote/local public
network, remote/local private network) then it means network determined user
busy. When used with any other location, then it means circuit congestion,
and the existing mapping proposed in the document applies.

As the identification of user busy is an important consideration to the
calling user in what to do next - invoke a further service etc. then this
condition should be reflected in the mapping.

Keith

Keith Drage
Lucent Technologies
Tel: +44 1793 776249
Email: [email-masked]

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From: "Peterson, Jon" <[email-masked]>
Date: Wed, 12 Dec 2001 11:34:19 -0600

Thanks for your comments, Keith.

Cause location is discussed at the beginning of 6.2.4.1 and 7.2.6.1 - if the
wording there needs to be strengthened we'd appreciate a suggestion. Note
that we are willing to create exceptions to our blanket statement on cause
location behavior - we do so, for example, for cause code #21 (see bottom of
pg 21).

Our analysis of cause codes derives entirely from Q.76x and its references
to Q.850. While I appreciate that there are a number of ways that cause
codes are used in various networks, we've tried to restrict the mapping to
the standard meanings of these values. Q.850 defines cause #34 as 'No
circuit/channel available'. It isn't clear to me why the sort of scenario
you're describing wouldn't use cause #17 with a non-user location. Q.850
does seem to contradict the ITU-T I.220 reference on the restriction on #17
- in fact, Q.850 on #17 says: "This cause value may be generated by the
called user or by the network."

Jon Peterson
NeuStar, Inc.

> -----Original Message-----
> From: Drage, Keith (Keith) [mailto:[email-masked]]
> Sent: Wednesday, December 12, 2001 9:40 AM
> To: [email-masked]
> Subject: [Sipping] ISUP draft: Issue on cause code mapping
> 
>