IMS is an architecture that enables operators to offer advanced multimedia services across circuit-switched and packet-switched networks using SIP for call signaling. It provides a layered approach separating the services, control, and transport planes. 3GPP has specified and enhanced IMS in successive releases to support additional networks and services. IMS allows for convergent applications across networks using common resources and control through SIP. This provides a consistent experience to subscribers regardless of access network.

1. IMS High Level Presentation
Created by: Rogelio Gomez – May 2011
http://ar.linkedin.com/in/rogeliogomez

2. Definition of IMS…
• IP Multimedia Subsystem (IMS) is an architecture
that enables operators to offer a new generation of
advanced multimedia services
– Across both circuit and packet switched networking
infrastructures
• IMS is a standard that defines an architecture that
uses SIP for call signaling between network
elements
– Provides a layered approach with separated services,
control, and transport planes

3. 3GPP Experience
- 3GPP specified IMS as part of Rel 5 with
improvements in Rel 6
- 3GPP specified UMA as part of Rel 6
- 3GPP added support for I-WLAN in Rel 6
- 3GPP is enhancing IMS to support fixed
broadband in Rel 7
- 3GPP adding Voice Call Continuity in Rel 7
Many IMS based optimizations in Rel 7
IMS Based Multimedia services in Rel 7
Rel 5 Rel 6 Rel 7 Rel 8
1999 2002 2003 2004 2005 2006 2007 2008

4. IMS – The simple View
Key Elements:
AS – Application Server
Application Application
Application MRFC - Multimedia
Server Server Server Resource Function
Controller
MRFP - Multimedia
Resource Function
Processor
MRF – Media Resource
Function
S-CSCF
HSS
CSCF- Call Session
SIP Control Function
I-CSCF
BGCF BGCF - Breakout Gateway
Control Function
P-CSCF MGCF - Media Gateway
MGCF
MRFC Control Function
CSCF
MGW - Media Gateway
HSS - Home Subscription
MRFP MGW Server
RTP
MRF

5. Key IMS Concepts
• Multiple Plane Architecture
– Makes use of separate planes:
• Application, Transport and Session Control
• Centralized Database
– Single point for all users data HSS. With the use of Diameter
protocol and HSS (Home Subscriber Server) to validate users
• The Subscribers Services are independent of the Access Method
– Enables support for PSTN, 3G mobile, WiFi, GPON, etc.

6. IMS Benefits
Convergent Applications
Convergent Applications Applications
•• Across Networks
Across Networks
•• Reduced development costs and time
Hosted
Reduced development costs and time
•• Voice, Video and data services
Services
Voice, Video and data services
•• Write once // use many
Write once use many Video
Data Voice
Common Resources
Common Resources Control
•• Media server resources
Media server resources
•• Common user data
Common user data
•• Single user profile across applications
Single user profile across applications SIP
•• Integrated applications
Integrated applications
Transport
Control point
Control point
•• Common Session Control (SIP)
Common Session Control (SIP)
•• Provides common service policies
Provides common service policies
•• Leverages investments across multiple
Leverages investments across multiple
applications
applications Access
Any Access Network
Any Access Network DSL Mobile PSTN
•• Eliminates multiple service solutions
Eliminates multiple service solutions CMTS
•• Network transparency
Network transparency
•• Consistent services across networks
Consistent services across networks

7. The need of IMS
• Need a better environment for creating and deploying
high value multimedia services
• Transform business models from voice-driven to service-driven
businesses
• Fixed-Mobile Convergence on a common IP application and service
delivery architecture
• Grow and protect subscriber base, increase ARPU
(Average Revenue Per User)
• Deliver a differentiated portfolio of value-added services
• Provide more subscriber focused offerings
• Controlling CAPEX and OPEX
• Maturity and adoption of SIP and XML
• Web model development model shortens the required investment of a
programmer to develop new applications
• Enables best-of-breed solutions with focus on new IP application services
• Fast time to market for new services
• Develop on standards-based technology
• Reduce time to market for new applications with web development model

8. IMS Applications
Unified Video
Announcements Video Mail
Messaging Conferencing
IP
Phones Pre-Paid Voice Mail Conferencing Video Ringback
SIP SIP
SIP
3G
S-CSCF /
SCIM
SIP Routing Cloud
2.5G IP MSC SIP MGCF
RTP MRFSIP
PSTN MGW
Cable CMTS

9. Important IMS Applications
Scenarios
• FMC – Fixed Mobile Convergence
• IP Centrex Hosting for Businesses
• Audio and Video combined with other services
– For example, conferencing, push-to-communicate,
Multimedia over Broadband, Multimedia IM
• Legacy Migration to Unified Platform
– Voice mail, conferencing, SMS, Prepaid Services

10. Thank you!