IMS and SIP Signalling with EPS and UMTS Access

Contents:

The IMS and SIP Signalling with EPS and UMTS Access Access course provides a thorough and fairly detailed understanding of the architectures, functions and protocols in IMS as specified by 3GPP for the GERAN/UTRAN access.

Signalling flows of relevant traffic cases for the IMS architecture are studied. Especially the SIP signalling and the SDP exchange are examined from different aspects, on overview level as well as in some depth, analysing the parameters used in the SIP messages and responses.

Pre-Requisites:

General knowledge of the GSM/UMTS Core Network’s architecture, mode of operation and terminology as well as the Internet Protocol (IP) is recommended. For required background knowledge, we recommend Apis’ GSM/UMTS/EPS System Overview and TCP/IP in Mobile Networks courses.

Network Overview

• An overview of the access network evolution and the protocols and addresses used

• Codecs: EFR, AMR and AMR-WB

Voice over IP – basics

• Control plane: SIP and SDP

• User plane: RTP and RTCP

• Basic SIP concepts and nodes

• PSTN breakout; the MGC and MGW

IMS Architecture

• How 3GPP uses SIP in IMS

• Introduction of the P-, I-, and S-CSCF nodes

• The HSS and SLF nodes and the Cx and Dx reference points

• The AS node and the Filter Criteria

• Identities, including ISIM, IMPI and IMPU

• SIP URI and tel URI usage; implicit registration set and the use of Alias identities

• Usage of GRUU

• Basic SIP signalling flows: Registration and Session Initiation

SIP extensions used in IMS

• Methods and messages used in IMS to extend basic SIP; e.g. P-Headers, 100rel, path, precondition, compression, privacy, sec-agree and preferences

• DNS usage in SIP; SRV and NAPTR records

• ENUM usage

• IMS Register and Invite signalling flows with the 3GPP extensions. A trace is presented for illustration

DIAMETER

• The Diameter base protocol

• Diameter usage on the Cx and Dx reference points

• The iFC and the use of Service Profiles

Security

• The IMS security architecture, including the SEG and the use of UMTS AKA

• IMS usage of IPsec ESP and IKE

• GPRS-IMS Bundled Authentication (GIBA)

Interworking

• PSTN/CS breakout; the BGCF, IMS-MGW and MGCF nodes and the H.248 protocol

• IP/PS interworking; the use of a B2BUA

• IPv6 and IPv4 interworking; the IMS-ALG and the TrGW

• The support for NAT in IMS

Charging

• Policy and Charging Control (PCC) usage for charging information transfer to the online and offline charging nodes

Quality of Service

• The UMTS end-to-end QoS approach

• Policy and Charging Control (PCC) usage for QoS handling

Services

• The IMS Service Provisioning Architecture; the SIP methods Refer and Publish. How to route on Public Service Identity (PSI)

• Multimedia Telephony Service, IMS Centralized Services and Service Continuity

• SIP usage in Presence, Push-to-Talk, Conferencing, Supplementary Services, Combinational Services and Messaging

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