Re: [Sipping] draft-mahy-iptel-cpc

Martin,

Sorry my choice of words. 'back to ISUP' was not meant to imply a
backward direction message but where the interworking from SIP -> ISUP.

ISUP -> SIP working is easy as ISUP will only contain one value but if
SIP contains multiple values as Paul has suggested then we need to be
able to map these to a single value in ISUP.

Ian Elz

System Manager
DUCI LDC UK
(Lucid Duck)

Office: + 44 24 764 35256
gsm: +44 7801723668
ian.elz@ericsson.com

-----Original Message-----
From: DOLLY, MARTIN C, ATTLABS [mailto:mdolly@att.com] 
Sent: 01 April 2008 13:16
To: Ian Elz; iptel@ietf.org; sipping@ietf.org
Subject: RE: [Sipping] draft-mahy-iptel-cpc

Ian,

CPC: Information sent in the forward direction indicating the category
of the calling party and, in case of semiautomatic calls, the service
language to be spoken by the incoming, delay and assistance operators.
The format of the calling party's category is shown below.

OLI:  Information sent in the forward direction indicating toll class of
service. Identification of the originating line.

Martin

-----Original Message-----
From: Ian Elz [mailto:ian.elz@ericsson.com] 
Sent: Tuesday, April 01, 2008 4:58 AM
To: Paul Kyzivat
Cc: iptel@ietf.org; DOLLY, MARTIN C, ATTLABS; sipping@ietf.org
Subject: RE: [Sipping] draft-mahy-iptel-cpc

Paul,

My comments are made based upon the content of the latest draft (06).

The introduction begins:

   "SS7 ISUP [4] defines a Calling Party's Category (CPC) parameter that
   characterizes the station used to originate a call and carries other
   important state that can describe the originating party.  When
   telephone numbers are contained in URIs, such as the tel URI [2], it
   may be desirable to communicate any CPC associated with that
   telephone number or, in the context of a call, the party calling from
   it."

Based upon this the current requirement appears to be to support the
ISUP CPC/OLI.

If the requirement is greater than this then that is a discussion that
we should have before the draft is finalized.

The issue with mutual exclusivity exists in the current ISUP
implementations. If that limitation is to be overcome then that
requirement also needs to be discussed. If we are to move from mutual
exclusivity of values then we need to ensure that interworking back to
ISUP is supported. The resolution of the overlapping cases as you have
indicated may have to be at the discretion of the network operator.

Ian Elz

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