40545 «IMS Signaling»

Course Code




This course provides a detailed introduction to signaling on IMS and the protocols involved in different traffic cases. This includes SIP (Session Initiated Protocol), SDP (Session Description Protocol), Diameter protocol and IMS related Diameter applications, H248/GCP/MEGACO. Other related protocols and IMS applications are briefly explained e.g. DNS, Diameter and RTP.


Learning objectives

On completion of this course the participants will be able to:

  • Describe the IMS, IP Multimedia Subsystem, architecture.
  • Describe the role of standard bodies.
  • Describe the concepts related to mobile and fixed access to IMS.
  • Describe the main protocols, signaling flows and node functions for typical IMS Sessions
  • Describe the basic functions and capabilities of SIP and why SIP is required in IMS.
  • Describe the function of SIP Components, SIP Proxies and SIP User Agents (UAC, UAS).
  • Explain stateful and stateless SIP Proxies.
  • Describe the specifications, functions and usage of all the SIP Methods and the more common SIP Responses.
  • Explain SIP Transactions and Dialogs.
  • Explain Telephone numbers, SIP-URIs, Tel-URLs for addressing end-users.
  • Explain the routing and addressing principles of SIP messages and the function of the SIP routing header fields (Request URI, Via, Route, Record-Route, Contact and others).
  • Describe the function and uses of the more common SIP header fields used in IMS and their related RFCs.
  • Describe the Registration process, including Authentication.
  • Describe SIP to SIP and SIP to ISUP Session establishment.
  • Describe SIP/ISUP interworking including specifications, and the function and use of Number Normalization, ENUM and External Network Selection (Breakout – BGCF).
  • Explain SIP forking.
  • Analyze detailed SIP IMS signaling flows and Message content for Registration, Session Establishment and other call scenarios.
  • Understand and describe the structure, specifications and usage of Session Description Protocol (SDP) in IMS.
  • Explain the function of SDP and the offer / answer model for SDP in IMS.
  • Describe the steps in a generic session establishment
  • Describe the use of RTP/RTCP in IMS
  • Describe the function of DNS in IMS.
  • Describe the basic functions and capabilities of Diameter
  • Describe the structure of Commands.
  • Describe the structure, types and format of AVPs.
  • Describe the main Diameter base protocol messages and AVPs.
  • Describe the services provided by the Cx/Dx and Sh Diameter applications for IMS
  • Understand and describe the structure, specifications and usage of H248 (MeGaCo)
  • Describe typical H248 signaling sequences in IMS and their relationship with SIP and ISUP signaling.
  • Describe the steps during a registration procedure and in a basic call
    set up SIP to SIP 


Target audience

The target audience for this course is System Technicians, Service Technicians, System Engineers, Service Engineers.



It is recommended that the participants will be familiar to basic telecom concepts and have knowledge equivalent to the “IMS basic course”


Duration and class size

The recommended length of the course is 3-4 days depending on the participants’ background. The maximum number of participants is 16.


Learning situation

This course is based on theoretical instructor-led lessons given in a classroom environment.