29 chapters · 120+ hand-built diagrams · Kindle-style reader

VoNR & IMS — 5G voice, decoded bit by bit

The complete engineer's guide to voice on 5G: the IMS, SIP/SDP, registration, the 5QI-1 QoS flow, the end-to-end VoNR call, EPS fallback, mobility, VoWiFi, emergency calling, roaming, security, charging, KPIs and SIP/RTP troubleshooting — explained with the depth practitioners actually need.

29chapters · 6 parts
120+hand-built diagrams
6appendices + labs
lifetime access
$4.99₹499
CAFETELE · THE ENGINEER'S HANDBOOK
VoNR & IMS Engineering
Complete 5G Voice, Emergency Calling & Roaming Guide
V
by Abhijeet Kumar
29 chapters · 6 appendices · 120+ diagrams
Grounded in 3GPP · IETF SIP/RTP · GSMA IR.92/NG.114 Instant online access Lifetime — one-time payment Free 4-chapter preview
What's inside

A working model of 5G voice, end to end

Not a glossary and not a slide deck — a structured build-up from why a voice packet is special to signing off that a network can carry it. Every chapter ends with a summary and interview-grade review questions.

IMS & SIP/SDP

The CSCFs, TAS, HSS/UDM, MRF and the SBC — and SIP/SDP read line by line, so any voice trace becomes a transcript you can follow.

Registration & the call

IMS & 5G registration, the IMS PDU session and P-CSCF discovery, and the full SIP INVITE flow with preconditions — traced message by message.

QoS & media

5QI-1/GBR/ARP, the PCF and PCC rules that build the voice flow, the RTP/RTCP path and SBC anchoring, and codecs (AMR/EVS, DTX, DTMF).

EPS fallback & mobility

Why most "5G calls" are fallback today, redirect vs N26 handover, voice-interruption analysis, SRVCC, and VoWiFi over ePDG/N3IWF.

Emergency, roaming & security

5G emergency calling with location, S8HR/SEPP roaming voice, IPsec/SRTP and lawful intercept, plus online/offline charging.

Troubleshooting & KPIs

Decode SIP failures, hunt one-way audio, cut setup delay, design VoNR KPIs, read QXDM/UE logs and Wireshark — then the operator launch checklist.

Try before you buy

Read the whole Foundations part — free

Chapters 1–4 — the voice problem, the IMS architecture, SIP/SDP, and the three voice modes — are completely free, no signup. Open the Kindle-style reader, switch between paper, sepia and dark themes, and judge the depth before you spend $4.99.

The reader feels like Kindle, reads like a senior engineer

A fixed chapter sidebar, three reading themes, font sizing, reading progress, and 120+ diagrams that re-theme with the page. Built for long, focused reading — on desktop and mobile.

paper · sepia · dark120+ SVG diagramsreview questionsmobile-ready
Open free preview
Table of contents

29 chapters across 6 parts

Plus 5 appendices: a full glossary, the standards bodies map, a hands-on open-source lab guide, 50 interview questions, and reusable reference-architecture templates.

PART I

Foundations of IMS & 5G Voice · FREE

  • The voice problem: CS → VoLTE → VoNR
  • IMS architecture — CSCFs, TAS, HSS, MRF, SBC
  • SIP & SDP fundamentals
  • VoLTE vs VoNR vs EPS fallback
PART II

Identity, Registration & Session Setup

  • IMS registration & AKA
  • 5G registration for a voice UE
  • The IMS PDU session & P-CSCF discovery
  • The SIP INVITE flow & preconditions
PART III

QoS, Bearers & the Media Path

  • 5G QoS for voice — QFI, 5QI-1, GBR, ARP, PDB
  • Dedicated QoS flow & PCF / PCC rules
  • RTP/RTCP & SBC / IMS-AGW anchoring
  • Codecs — AMR-NB/WB, EVS, DTX, DTMF
PART IV

Calls, Mobility & Special Services

  • The VoNR call · EPS fallback · mobility & SRVCC
  • Voice over Wi-Fi (ePDG / N3IWF)
  • Emergency calling in 5G
  • SMS/RCS · supplementary services (MMTEL)
PART V

Roaming, Security & Charging

  • Roaming voice — S8HR vs LBO, N9, SEPP
  • IMS & voice security — IPsec, SRTP
  • Lawful interception
  • Charging — online/offline, Ro/Rf, CHF
PART VI

Optimization & Troubleshooting

  • SIP failures · one-way audio · setup delay
  • VoNR KPI design & assurance
  • UE-log (QXDM) & Wireshark SIP/RTP labs
  • Operator VoNR launch checklist
APPENDICES

Reference & Practice

  • Glossary · SIP header & method reference
  • 5QI/QCI/ARP tables · SIP response codes
  • 30 interview questions
  • Open-source IMS + 5G voice lab
Who it's for

It bridges the two worlds — telecom and cloud-native

Telecom engineers going cloudRAN & core engineers who need Kubernetes, GitOps and the cloud-native 5G core in their own language.
Cloud & DevOps engineers entering telecomUnderstand why telco workloads aren't ordinary IT — determinism, the UPF, PTP timing, five-nines.
Architects & decision-makersPlacement, vendor evaluation, migration sequencing and the economics that decide what survives.
Students & interview-prepA structured model plus 50 interview questions and a buildable open-source capstone.
Get the book

One book. Lifetime access. ₹499 / $4.99

A one-time payment, instant online access, free updates. Read the free preview first to confirm it fits.

CafeTele Engineering Book

VoNR & IMS Engineering — full access

₹499₹2,499
One-time payment · lifetime access · instant unlock
  • All 29 chapters + 5 appendices unlock instantly
  • 120+ hand-built diagrams · Kindle-style reader
  • Free updates · read on any device
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Questions

Frequently asked

Can I preview it first?

Yes — chapters 1 to 4, the entire Foundations part, are completely free with no signup. Open the reader, try all three themes, and confirm the depth before you buy.

How do I read it after I buy?

Instant online access. After payment via Razorpay the full 29-chapter Kindle-style reader unlocks immediately in your browser — chapter sidebar, three themes, font sizing, progress tracking — with lifetime access. No subscription, no recurring fees.

₹499 or $4.99 — which do I pay?

₹499 if you pay from India, $4.99 internationally. Pick your currency on the buy panel above. One-time payment, lifetime access.

Is it based on real standards?

Yes. It is grounded in 3GPP (TS 23.228 IMS, TS 23.501/23.502 5GS, TS 24.229 SIP profile), the IETF SIP/SDP/RTP RFCs, and GSMA IR.92/IR.94/NG.114 — focused on the architecture, procedures and troubleshooting an engineer actually uses.

Do I need deep prior knowledge?

Basic 4G/5G architecture familiarity helps, but Part I builds the foundations from scratch — from why voice is special to the IMS and SIP. RAN, core, voice, test and optimization engineers all get value.

Is there a hands-on lab?

Yes. Chapter 22 and Appendix C walk you through standing up a complete 5G network on a laptop with free open-source tools — Open5GS/free5GC, UERANSIM, Kubernetes, Prometheus — and fourteen labs tied to the chapters.

What's the refund policy?

Because it's a digital product with instant access and a free 4-chapter preview, sales are final once unlocked. Please read the free preview first to confirm it fits your needs.

The network is being rebuilt — understand it.

29 chapters, 120+ diagrams, a Kindle-style reader and lifetime access — for less than a coffee.

Get the book — $4.99 / ₹499