Internet DRAFT - draft-haluska-dispatch-csi-needed
draft-haluska-dispatch-csi-needed
DISPATCH J. Haluska
Internet-Draft Telcordia
Intended status: Informational February 16, 2010
Expires: August 20, 2010
The Need to Convey Carrier Selection Information in SIP
draft-haluska-dispatch-csi-needed-00
Abstract
This draft documents a need for the ability to signal Carrier
Selection Information, which identifies how the carrier chosen for a
call was selected, using SIP, and identifies a documented though not
yet standardized mechanism which addresses this need.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Normative References . . . . . . . . . . . . . . . . . . . 8
6.2. Informative References . . . . . . . . . . . . . . . . . . 8
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
This draft documents the need for the ability to signal Carrier
Selection Information, which identifies how the carrier chosen for a
call was selected, using SIP, and identifies a documented though not
yet standardized mechanism which addresses this need.
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2. Problem Statement
In the PSTN, Interexchange Carriers (IXCs) provide services including
routing calls between different networks. In North America,
subscribers can presubscribe to a particular IXC to handle calls by
default. The IXC may be selected by other means. For example, the
caller may dial a specific prefix identifying the desired IXC.
When calls involving IXCs are made, it is required to record not only
the IXC used for the call, but also the method by which that IXC was
selected. Thus, this information needs to be conveyed in signaling.
In ISUP this is conveyed using the Carrier Selection Information
(CSI) parameter.
Services currently implemented in the PSTN including Operator
Services and Directory Assistance make use of the ISUP CSI parameter,
e.g. for usage collection purposes. Such services are migrating to
SIP based platforms, and the need for exchanging this information in
signaling still exists.
Current SIP-ISUP interworking standards do not specify a SIP mapping
for the CSI parameter. Thus, when interworking from ISUP to SIP, the
CSI parameter is carried in an encapsulated ISUP message in a MIME
body.
For SIP originated calls, there is currently no standardized way to
carry this information.
The "dai" tel URI parameter described in [I-D.draft-yu-tel-dai-08] is
intended to convey this information in SIP. This parameter, if
standardized, would provide a mechanism allowing for the exchange of
this information using SIP.
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3. Conclusion
In environments such as the North American PSTN where carrier
selection is implemented, there is a need to convey how the chosen
carrier was selected. This information is still needed going forward
using SIP. The "DAI" parameter defined in [I-D.draft-yu-tel-dai-08]
can be used to exchange this information.
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4. IANA Considerations
This memo includes no request to IANA.
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5. Security Considerations
There are no security considerations associated with this document.
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6. References
6.1. Normative References
6.2. Informative References
[I-D.draft-yu-tel-dai-08]
Yu, J., Hancock, D., and F. Andreason, "DAI Parameter for
the "tel" URI", 2009.
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Appendix A. Acknowledgements
The author would like to thank Martin Dolly, Gary Munson, and the
members of the Operator Services Technical Forum.
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Author's Address
John Haluska
Telcordia
331 Newman Springs Road
Red Bank, NJ 07701
USA
Phone:
Email: jhaluska@telcordia.com
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