Transcript 3GPP_Architectural_Overview

3GPP Architectural Overview
SDO Emergency Services Coordination Workshop (ESW07)
Jefferson Building of the Library of Congress , Washington DC
April 10-12, 2007
Gary Jones – Director of Standards Policy
T-Mobile USA
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Architectural Model
Le (e.g. E2)
LRF
2. Location &
Routing Function
from PSAP
to PSAP via IP
mutimedia
Network
Ml
Mm
UE
Gm
P-CSCF
Mw
1. SIP INVITE
SIP REGISTER
Mw
E-CSCF
Mi/Mg
3. SIP INVITE
or ISUP IAM
to PSAP
(via PSTN
via BGCF/
MGCF)
Registration
Outgoing Call
S-CSCF
Mm/Mw
Callback
Visited Network
2. SIP INVITE
Home Network
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1. SIP INVITE
from PSAP
Main Elements
• UE - in UMTS (3G) mobile telephone systems is the name given
to the User Equipment
• E-CSCF – Emergency Call Session Control Function handles
certain aspects of emergency sessions, e.g. routing of
emergency requests to the correct emergency center or PSAP
• P-CSCF – Proxy CSCF is the first point of contact for the IMS
terminal. It can be located either in the visited network (in full
IMS networks) or in the home network (when the visited network
isn't IMS compliant yet)
• S-CSCF – Serving CSCF is the central node of the signaling
plane. It's a SIP server, but performs session control as well. It's
always located in the home network.
• LRF – Location Retrieval Function is a functional entity handles
the retrieval of location information for the UE
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3GPP Architecture Characteristics
• Call establishment and registration support in the visited
network (not home network unless non-roaming)
• Routing to a PSAP based on location information
provided by the UE or obtained by the LRF (e.g. using
SUPL or the existing 3GPP control plane solution)
• Conversion of location to a PSAP URI is currently
implementation dependent although IETF Ecrit Location to
Service Translation (LoST) Protocol is a possible candidate
• Call back from the PSAP (if needed) is via the home
network S-CSCF and visited network P-CSCF and is
based on the initial emergency registration (or normal
registration if the UE is not roaming)
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