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		# IMS Signalling flows

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		# Network Simulation

Registration IMS Signalling flows
Non Hiding
P-CSCF subscription for registration state event package

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Start

IMS Signaling Flows

Registration: Non Hiding

#	User not registered

#	Reregistration

#	Subscription by UE

#	Subscription by P-CSCF

#	Deregistration by S-CSCF

#	Deregistration by HSS

#	Network-initiated deregistration

#	Network initiated re-authentication

Registration: Hiding

#	User not registered

#	Mobile initiated deregistration

Session Initiation: Non Hiding

#	MO#1a / S-S#1a / MT#1a

#	MO#2 / S-S#2 / MT#2

#	CS-O / S-S#2 / MT#2

#	MO#2 / S-S#3 / CS-T

#	MO#2 / S-S#2 / MT#1c

Session Initiation: Hiding

#	MO#1b / S-S#2 / MT#2

#	MO#2 / S-S#1b / MT#2

#	MO#2 / S-S#1c / MT#2

#	MO#2 / S-S#1d / MT#2

Non Hiding -- P-CSCF subscription for registration state event package

1) SUBSCRIBE

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-	This example describes the subscription procedure for the network initiated deregistration event, whereby the P-CSCF requests to be notified by the S-CSCF when the event has occurred.

-	It is assumed that the user has registered prior to initiating subscription of an event. For this example the trigger point at the P-CSCF for sending out the SUBSCRIBE request is the 200 (OK) response of the user's registration.

-	P-CSCF1 performs the DNS queries to locate the I-CSCF in the home network. The look up in the DNS is based on the address specified in the Request URI.


1a) from P-CSCF1 to I-CSCF1	(a)	(b)	Prev	Next	Up

-	From: This header is populated with the SIP URI that identifies the P-CSCF.

-	Contact: This is where the NOTIFY requests for this subscription will be sent.

-	Event: This field is set to the value 'reg' to specify the use of the reg event package.

-	I-CSCF1 sends a query to the HSS to find out the S-CSCF of the called user. The HSS responds with the address of the current S-CSCF for the terminating subscriber.


1b) from I-CSCF1 to S-CSCF1	(a)	(b)	Prev	Next	Up

Non Hiding -- P-CSCF subscription for registration state event package

2) 200 OK

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S-CSCF1 first authorizes the subscription. As S-CSCF1 can trust the content of the P-Asserted-Identity header and <sip:pcscf1.visited1.net> is on the list of the authorized users for the "reg" event package stored by S-CSCF1, therefore S-CSCF1 sends an acknowledgement towards I-CSCF1 indicating that the subscription was successful.


2a) from S-CSCF1 to I-CSCF1	(a)	(b)	Prev	Next	Up

-	Expires: If the value of the Expires header in SUBSCRIBE request is different from the one received in REGISTER method, then the value of Expires header in the 200 (OK) response is set to match the value of Expires header in REGISTER method.


2b) from I-CSCF1 to S-CSCF1	(a)	(b)	Prev	Next	Up

Non Hiding -- P-CSCF subscription for registration state event package

3) NOTIFY

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-	S-CSCF1 sends a first NOTIFY request towards P-CSCF1 in order to inform P-CSCF1 about the registration status of the monitored user.


3a) from S-CSCF1 to P-CSCF1	(a)	Next	Prev	Up

-	From: The tag of this field matches that of the "To" field in the received 200 (OK) response for the SUBSCRIBE request.

-	Content-Type: Set to the value of the Accept header received in the SUBSCRIBE request or "application/reginfo+xml" if the Accept header was not present in the SUBSCRIBE request.

Non Hiding -- P-CSCF subscription for registration state event package

4) 200 OK

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4a) from P-CSCF1 to S-CSCF1	(a)	Next	Prev	Up

Last update: November 19, 2009

focus on internet & telecom standardization topics

Registration IMS Signalling flows Non Hiding P-CSCF subscription for registration state event package

Registration IMS Signalling flows
Non Hiding
P-CSCF subscription for registration state event package