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		# SIP RFC3261's Example

		# SIP Protocol Structure

		# SIP Dialogs & Routing

		# SIP Service Examples

		# SIP Authentication Service

		# ABNF Grammars

		# IMS Signalling flows

		# 2G-3G Network Evolution

		# Cryptography Basics

		# SSL/TLS Sequence Charts

		# PKI Certificate Examples

		# PKI's ASN.1 Definitions

		# CMS Examples

		# CMS's ASN.1 Definitions

		# Network Simulation

Registration IMS Signalling flows
Non Hiding -- Network-initiated deregistration upon UE roaming and registration to a new network

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 -- Network-initiated deregistration upon UE roaming and registration to a new network

1) REGISTER (via P-CSCF2)

-	This shows the registration signalling flow for the scenario that UE1 loses the GPRS attachment in current visited access network and roams to makes a new GPRS attachment in a new visited access network without deregistration from its previous network. When UE1 starts registration via the new visited access network and P-CSCF2, the home S-CSCF in the home IMS network initiates the deregistration to P-CSCF1 in the previous visited network. It is assumed that the old P-CSCF has subscribed the event package to the S-CSCF and the subscription has not expired.

-	For the reason of simplicity, the authentication procedure is not shown because it has no technical impact on this flow.


1a) from UE1 to P-CSCF2		(a)	(b)	(c)	(d)	(e)	(f)	Prev	Next	Up


1b) between P-CSCF2 and DNS		(a)	(b)	(c)	(d)	(e)	(f)	Prev	Next	Up


1c) from P-CSCF2 to I-CSCF1		(a)	(b)	(c)	(d)	(e)	(f)	Prev	Next	Up


1d) between I-CSCF1 and HSS		(a)	(b)	(c)	(d)	(e)	(f)	Prev	Next	Up


-	I-CSCF1 sends the Cx-Query signalling flow to the HSS (Visited Network Identifier, subscriber identity, home domain name,). Because user has not deregistered with its previous network, HSS finds a S-CSCF assigned for that user and treats this as a re-registration procedure. Therefore, the HSS returns S-CSCF1 name to I-CSCF1.


1e) from I-CSCF1 to S-CSCF1		(a)	(b)	(c)	(d)	(e)	(f)	Prev	Next	Up


1f) between S-CSCF1 and HSS		(a)	(b)	(c)	(d)	(e)	(f)	Prev	Next	Up


-	S-CSCF1 notifies the HSS to update its location information for that subscriber. The HSS sends a response to S-CSCF1 to acknowledge the update of location information and also with the user profile.

Non Hiding -- Network-initiated deregistration upon UE roaming and registration to a new network

2) 200 OK (REGISTER)


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


2b) from I-CSCF1 to P-CSCF2		(a)	(b)	(c)	Prev	Next	Up


2c) from P-CSCF2 to UE1		(a)	(b)	(c)	Prev	Next	Up

Non Hiding -- Network-initiated deregistration upon UE roaming and registration to a new network

3) NOTIFY P-CSCF1

-	As there was a change in the user's registration status and the old P-CSCF is still subscribed to the registration event package for that user, therefore, S-CSCF1 sends a NOTIFY request to P-CSCF1.


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

Non Hiding -- Network-initiated deregistration upon UE roaming and registration to a new network

4) 200 OK (NOTIFY)


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

Last update: November 19, 2009

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