New Book: The 5G Core - Architecture and Functions Explained (Paperback & E-Book versions)


Dear Readers,

I am thrilled to announce that my book, "The 5G Core: Architecture and Functions Explained: A Practical Guide to 5G Core Networks, Service-Based Architecture, and Integration with BSS/OSS" is now published and available on all major Amazon marketplaces.

Back Cover - The 5G Core: Architecture and Functions Explained: A Practical Guide to 5G Core Networks, Service-Based Architecture, and Integration with BSS/OSS
Back Cover - The 5G Core: Architecture and Functions Explained: A Practical Guide to 5G Core Networks, Service-Based Architecture, and Integration with BSS/OSS

This is a moment I have been working toward for a long time. What started as articles on this website has grown into a comprehensive guide that I believe will help professionals across the telecom industry navigate the complex world of 5G Core networks.

Why I Wrote This Book

I have seen too many professionals struggle with 5G Core. Some come from 4G backgrounds and try to map familiar concepts directly. They look for the MME and are confused when they find AMF instead. They expect Diameter and encounter HTTP/2.

This book bridges that gap. It starts from absolute fundamentals and builds up to advanced concepts, always keeping the practical, real-world perspective that I have developed over years of implementing these systems.

What Makes This Book Different 

If you have been reading this website, you already know my style. I believe complex topics can be made accessible when explained clearly, with attention to both the "what" and the "why."

This book brings that same approach to every chapter:

Core Architecture

  • Service Based Architecture (SBA) explained in simple terms
  • Deep dives into major 5GC functions: AMF, SMF, UPF, PCF, NRF, UDM, AUSF, NSSF, NEF, CHF
  • Complete Call flows for registration and PDU session establishment
  • How Network Slicing enables customized services for different use cases

Network Operations

  • 5G Identifiers, Subscription management, and Protocols
  • Dedicated chapter on integration with OSS - Management, orchestration, and closed-loop automation
  • Dedicated chapter on 5G Roaming - Home Routed vs Local Breakout, SEPP security, N32 interface, and interworking with 4G

Interworking and Billing

  • Dedicated chapter on integration with BSS - How the Converged Charging System, Nchf, and NEF enable service Monetization
  • Interworking with 4G Networks through N26 and EPS Fallback
  • Charging and billing for roaming, including TAP and BCE settlement

The chapters on BSS integration and OSS integration are particularly special. These are topics rarely covered in depth elsewhere, yet they are essential for anyone building complete 5G solutions.

Who This Book Is For

This book is written for:

Solutions Architects: A complete mental model of how 5GC components fit together and integrate with BSS/OSS
Product Managers: Understanding of what 5G capabilities can be monetized and how
BSS/OSS Professionals: Clear guidance on integrating business and operations systems with 5GC
Network Engineers: The ability to configure and troubleshoot 5GC functions with confidence
Students: A solid foundation in 5G technology that bridges theory and practice
Anyone moving from 4G to 5G: A clear understanding of what changed and why

The Journey to This Book


For those who have followed my website (www.RajarshiPathak.com) over the years, you know that I have been sharing knowledge on subscription and usage monetization, BSS/OSS architecture, and 5G core networks for a long time.

In 2025, I had the privilege of speaking at the India Mobile Congress in New Delhi, where I showcased a joint solution on AI-Powered Dynamic Product Catalogue for Telecom BSS. That experience reinforced my belief that the telecom community grows stronger when we share knowledge openly.

This book is my way of giving back. It distills not just technical knowledge, but also the lessons learned from delivering multiple projects.

Where to Get the Book


The Paperback & EBook versions are now available on all major Amazon marketplaces:

Marketplace Link

Amazon.com (US) : [LINK]
Amazon.co.uk (UK): [LINK]
Amazon.de (Germany): [LINK]
Amazon.fr (France): [LINK]
Amazon.it (Italy): [LINK]
Amazon.es (Spain): [LINK]
Amazon.ca (Canada): [LINK]
Amazon.com.au (Australia): [LINK]
Amazon.com.au (Japan): [LINK]

For my Indian Audience: You can buy the E-Book version from Amazon.in website. Here is the [LINK].

I am in discussions with technical publishers in India who can distribute the paperback through local bookstores and online platforms. This would ensure the book is widely available at a reasonable price. 

Training and Consulting

If your team needs deeper training on any of the topics covered in this book, I offer one-on-one and group training sessions.

I offer exclusive training programs on end-to-end Telecom BSS and OSS, 5G charging, SaaS billing, and related topics including CRM, order management, convergent charging, policy control, provisioning, inventory, mediation, activation, service assurance, and more.

Contact me at admin@rajarshipathak.com for more information.

Thank You

To everyone who has supported this website over the years, who has attended my sessions, who has reached out with questions and feedback. This book exists because of you.

Let us continue learning together.

Rajarshi Pathak


The 5G Core: Architecture and Functions Explained
ISBN: 979-8251831801 (Paperback)

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