Vowifi & Wifi Calling: Architecture, Call Flows & Ims Core

Learn how VoWiFi works with IMS & EPC, explore IPsec tunnel, call flows, ePDG discovery, signaling & bearer mapping

What you'll learn

Understand how VoWiFi works and how it integrates with IMS and EPC core network elements.

Analyze VoWiFi architecture including ePDG, PGW, AAA, and IMS components like P-CSCF and S-CSCF.

Establish secure IPSec tunnels using IKEv2 and follow their setup process step-by-step.

Identify how default and dedicated bearers are created and mapped in VoWiFi service.

Explore key VoWiFi interfaces like SWu, S2b, SWm, SWx, and S6b with related protocols.

Follow VoWiFi call flows and signaling messages for registration and MO/MT call setup.

Learn how SIP URI, IMSI, FQDN, and APN work together in VoWiFi session management.

Troubleshoot common VoWiFi issues such as authentication failures and DNS resolution errors.

Requirements

Interest in telecom technologies and how voice services work over data networks.

Ability to follow call flows and signaling diagrams (no deep protocol expertise needed).

A basic understanding of mobile network concepts (2G/3G/4G/5G).

Description

Are you a telecom professional looking to master VoWiFi (Voice over WiFi) and understand how it integrates seamlessly into the IMS Core and Evolved Packet Core (EPC)? This course is your complete, practical guide to WiFi Calling — covering everything from basic concepts to advanced signaling flows, real-world deployment scenarios, and troubleshooting techniques.You'll begin by understanding what VoWiFi is, how it differs from VoLTE and 3G voice services, and why it’s increasingly essential for improving indoor coverage, call quality, and user experience. From there, the course dives into VoWiFi architecture, detailing the roles and interactions of core elements like UE, ePDG, PGW, AAA, P-CSCF, I-CSCF, S-CSCF, and HSS.You’ll gain in-depth knowledge of how IPSec tunnels are established, how default and dedicated bearers are managed, and how bearer mapping occurs between the EPC and the secure VoWiFi path. We’ll also explore how identifiers like IMSI, SIP URI, FQDN, and APNs are used to route and register VoWiFi sessions.The course covers all critical protocols and interfaces including IKEv2, GTP-C/U, and Diameter across SWu, S2b, SWm, SWx, and S6b interfaces. You’ll follow real-world call flow diagrams, SIP signaling sequences, and learn how to troubleshoot common issues in VoWiFi authentication, tunnel creation, and call setup.By the end, you'll be equipped to confidently analyze, design, and optimize VoWiFi services across mobile networks.This is a must-have course for any telecom engineer, system integrator, or technical trainer working with IMS and packet core networks.

Overview

Section 1: VoWiFi Basics: Concepts, Use Cases & Real-World Value

Lecture 1 VoWiFi Explained: What is WiFi Calling & How It Works

Lecture 2 Why VoWiFi Matters: Solving Indoor Coverage & Call Quality Issues

Section 2: VoWiFi vs VoLTE vs 3G: Technology, Call Quality & Network Impact

Lecture 3 VoWiFi, VoLTE & 3G: Key Technology Differences Explained

Lecture 4 Voice Quality Comparison: VoWiFi vs VoLTE vs 3G Performance Metrics

Lecture 5 Network Reach: Coverage & Service Availability Across VoWiFi, VoLTE, and 3G

Lecture 6 Architectural Comparison: IMS-Based VoWiFi vs Legacy Voice Systems

Section 3: VoWiFi Calling Essentials: Concepts, Prerequisites & Setup Needs

Lecture 7 VoWiFi Prerequisites: Device, Network & Core Network Capabilities

Lecture 8 Quick Intro to VoWiFi Calling: What It Is & How It Works

Section 4: VoWiFi Value: User Experience Gains & Operator Benefits

Lecture 9 VoWiFi Benefits for End Users & Mobile Network Operators (MNOs)

Lecture 10 Strategic Advantages of VoWiFi: From Indoor Coverage to Cost Savings

Section 5: VoWiFi Challenges: Technical Barriers, Limitations & Real-World Issues

Lecture 11 VoWiFi Deployment Challenges: Handover, QoS, Security & Device Limitations

Section 6: VoWiFi Core Architecture: Key Network Elements & Functional Roles

Lecture 12 Access Types in VoWiFi: 3GPP, Non-3GPP, Trusted & Untrusted Models

Lecture 13 UE Role in VoWiFi Architecture: Connectivity, Support & Limitations

Lecture 14 WiFi Access Point Function in VoWiFi: The First Connection Layer

Lecture 15 ePDG in VoWiFi: Role, Interfaces & IPsec Termination

Lecture 16 IPSec in VoWiFi: Secure Tunneling for IMS Access

Lecture 17 Step-by-Step: IPSec Tunnel Establishment in VoWiFi

Lecture 18 PGW Role in VoWiFi: Bearer Management & Policy Control

Lecture 19 PCRF in VoWiFi: Policy & QoS Control for IMS Traffic

Lecture 20 AAA Server in VoWiFi: Authentication, Authorization & Accounting

Lecture 21 P-CSCF in IMS: SIP Proxy Role in VoWiFi Call Setup

Lecture 22 I-CSCF in IMS: Entry Point for SIP Signaling in VoWiFi

Lecture 23 S-CSCF in IMS: Session Control in VoWiFi Services

Lecture 24 HSS in IMS: Subscriber Profile Management in VoWiFi

Section 7: Identifiers & Routing in VoWiFi: SIP URI, IMSI, FQDN & APNs

Lecture 25 SIP URI vs IMSI: Identity Handling & Session Targeting in VoWiFi

Lecture 26 FQDN in VoWiFi: Domain Resolution & DNS-Based Routing

Lecture 27 APNs in VoWiFi: IMS APN, Default Bearer & Data Path Setup

Section 8: VoWiFi Bearers Explained: IPsec Tunnel, EPC Mapping & QoS Flows

Lecture 28 VoWiFi Bearer Overview: Concepts, Functions & Flow Types

Lecture 29 IPSec Tunnel Setup in VoWiFi: Step-by-Step Signaling Flow

Lecture 30 Default Bearer Setup in VoWiFi: IMS APN Connectivity & QoS

Lecture 31 Dedicated Bearers in VoWiFi: Setup, QoS, and SIP Triggering

Lecture 32 Mapping EPC Bearers to IPsec Tunnel: Security & Flow Binding

Lecture 33 VoLTE vs VoWiFi Bearers: Architecture, Tunnel Use & QoS Control

Section 9: VoWiFi Protocol Stack: Interfaces, Protocols & Functional Mapping

Lecture 34 Overview of VoWiFi Interfaces & Protocols: Functional Layers & Roles

Lecture 35 SWu Interface in VoWiFi: IKEv2 Protocol for IPsec Tunnel Security

Lecture 36 S2b Interface Explained: GTP-C/U Role in Bearer Management

Lecture 37 Diameter Interfaces in VoWiFi: SWm, SWx & S6b Functional Breakdown

Section 10: VoWiFi Call Flows & ePDG Discovery: End-to-End Signaling Breakdown

Lecture 38 ePDG Discovery in VoWiFi: High-Level Process Overview

Lecture 39 ePDG Discovery: Detailed Signaling Message Flow in VoWiFi

Lecture 40 Initial Authentication Between UE & ePDG: Steps & Protocols

Lecture 41 Mobile-Originated VoWiFi Call Flow (Part 1): Signaling Path Initiation

Lecture 42 Mobile-Originated VoWiFi Call Flow (Part 2): SIP, Bearers & Media Path

Telecom engineers and network planners,Core network professionals (EPC, IMS, VoLTE),Students and fresh graduates in telecom