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IMS Registration Sequence Diagrams |
This sequence diagram details the message interactions involved in IMS
registration. IMS registration from a visited IMS network is covered. The
interactions covered are:
- Terminal attaching to the GPRS
Network.
- Terminal activates a PDP context.
- An unauthenticated IMS registration
is attempted.
- IPSec security association is
established between the User terminal and the P-CSCF.
- Finally the terminal performs an
IPSec protected registration that completes the authentication of the
network and the terminal.
 IMS
Registration
pdf
 IMS
Registration (Explore More) |
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IMS to IMS Call Flow |
A detailed IMS subscriber to IMS
subscriber is presented here. The preconditions for this call flow are:
- The calling IMS subscriber is
currently roaming outside the home network.
- The called user is registered in the
home network.
- The caller and the called user
require resource reservation before the call can be setup.
The major steps in the call flow are:
- IMS routing of the initial SIP
INVITE.
- IMS routing of the first response to
the INVITE.
- Resource allocation via PDP context
activation.
IMS
to IMS Call Flow
pdf  IMS
to IMS Call Flow (Explore More) |
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PSTN (ISUP) to IMS Interworking Call Flow |
This call flow covers the handling of a CS
network originated call with ISUP. In the diagram the MGCF requests seizure
of the IM CN subsystem side termination and CS network side
bearer termination. When the MGCF receives an answer indication, it requests
the IM-MGW to both-way through-connect the terminations. Originating and
terminating end initiated call releases are also covered.
PSTN
to IMS Call Flow
pdf PSTN
to IMS Call (Explore More) |
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IMS to PSTN (ISUP) Interworking Call Flow |
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This call flow describes the call setup from
an IMS subscriber to ISUP PSTN termination. The call is routed via the BGCF
(Border Gateway Control Function) to the MGCF (Media Gateway Control
Function). The MGCF uses one context with two terminations in IM-MGW (Media
Gateway). The termination RTP1 is used towards IMS Core network subsystem
entity and the bearer termination TDM1 is used for bearer towards PSTN CS
network element..
IMS
to PSTN Call Flow
pdf IMS
to PSTN Call (Explore More) |
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SDP Codec Selection and QoS Signaling in an IMS
Call |
Session Description Protocol (SDP) specifies
a format for exchanging streaming related parameters between SIP
subscribers. The following sequence diagram focuses on the SDP interactions
between two IMS subscribers. The flow covers two phases of the SDP
negotiation:
- Codec selection between the calling
and call IMS subscribers.
- SDP signaling involved in exchanging
quality of service information.
SDP
Codec Selection and QoS Signaling in an IMS call
pdf |
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IMS Presence Subscription and Notification Flow |
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IP Multimedia Subsystem (IMS) provides a
framework and building blocks for building advanced telecom services. One
such service is network wide publication and subscription of presence
information. Users can subscribe to presence information for their contacts.
If the contact accepts their request, the subscriber will be registered for
presence notification. Whenever the friend publishes presence information,
the IMS presence framework will notify the subscribed users.
IMS
Presence Subscription and Notification Flow
pdf
IMS
Presence Subscription and Notification (Explore More) |
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IMS Presence Resource List Subscription and
Notification Flow |
|
IP Multimedia Subsystem (IMS) provides a framework and building blocks for building advanced telecom services. One such service is network wide publication and subscription of
presence information. Users can subscribe to presence information for their contacts. If the contact accepts their request, the subscriber will be registered for presence notification.
Whenever the friend publishes presence information, the IMS presence framework will notify the subscribed users.
IMS presence information communication can put a lot of load on the network. One way to reduce this load is to predefine the list of friends and family. When you subscribe to the "friends
and family" list, a Resource List Server (RLS) in the IMS subscribes to the individual subscribers (presentities) on your behalf. Once the RLS completes the registrations, it collates the
individual presence status into a single NOTIFY message.
IMS
Presence Resource List Subscription and Notification Flow
pdf
IMS
Presence Resource List Subscription and Notification (Explore More) |
|
IMS Conference Call |
This sequence diagram shows an IMS user
creating a conference by using a conference-factory URI. The conference is
created at a MRFC/AS of the users home network. The steps involved in the
conference are:
- The conference initiator UE uses the
conference factory URI to initiate a conference with the MRFC/AS
(Multimedia Resource Function Control/Application Server).
- The MRFC/AS assigns a conference URI
to the conference and configures the MRFP (Multimedia Resource Function
Processor).
- The conference call is setup and the
RTP data begins flowing between the conference initiating UE and the
MRFP.
- The conference initiator then uses
the refer procedure to add more users to the conference. The new users
establish a call to the conference URI passed in the refer message.
- When the conference is in progress,
RTP media streams are being mixed and propagated to all the
participants.
IMS
Conference Call
pdf |
