Protocol Details from
3GPP TS 24.229
SDO Emergency Services Coordination Workshop (ESW06)
Columbia University, New York
October 5-6, 2006
Atle Monrad, Ericsson Mobile Platform
([email protected])
Stage-3 specification ’philosophy’
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3GPP TS 24.229 specifies the involved IMS entities
Reference relevant IETF-RFCs
Profile RFCs if only parts are supported
Specify additions and limitations
Work is ongoing and is planned to be completed by
mid-2007
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Involved entities
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UE - User Equipment
Proxy-CSCF
Serving-CSCF
Emergency-CSCF
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UE – User equipment
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Performs registration to the home IMS network
The emergency call is handled in the visiting network, thus a
dedicated emergency registration is needed when the terminal can
move out of the home network
Decides whether CS or IMS domain shall be used for initial
emergency call attempts
Can perform emergency call without SIM/UICC
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Open issues:
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when is a dedicated emergency registration needed?
How to indicate that location is not available?
How to transfer the equipment identifier?
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Proxy-CSCF
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Is the initial point for communication with terminals
Is access-agnostic
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Open issues:
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when is a dedicated emergency registration needed?
How can the P-CSCF discover whether the terminal is in the home
network?
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Serving-CSCF
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Is the central point in the home network handling the subscriber
Involved for emergency calls due to differences between normal
registrations and emergency registrations
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Open issues:
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No major
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Emergency-CSCF
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Is the interface towards the PSAP
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Open issues:
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How to mark an emergency session after the PSAP address has
been resolved between the E-CSCF - PSAP and the E-CSCF MGCF?
The use of the Resource-Priority header?
MGCF interworking; any regulatory requirements?
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Other issues
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Where shall the requirements on the PSAP be specified?
Call-back from the PSAP is currently not included.
The location is in current deployment often based on A-number
and cell-identity. Should LOST also consider these as ’valid
locations’, as existing databases in many cases are based on this?
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