Level 9

Voice over 5G (VoNR & IMS)

Deep-dive into Voice over New Radio — IMS architecture and SIP signaling, P-CSCF/I-CSCF/S-CSCF roles, IMS registration, VoNR mobile-originated and mobile-terminated call flows, QoS for voice (5QI=1), EPS Fallback, VoNR-to-VoLTE handover, video calling, and call-quality troubleshooting with MOS analysis.

0/15 lessons

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IMS Architecture for 5G

0/6

Understand the IP Multimedia Subsystem integrated with 5G Core — SIP signaling, CSCF roles (P/I/S-CSCF), TAS, MGCF, IMS registration over 5G, and how IMS and 5GC interwork.

IMS in 5G: architecture and role of each component

Full IMS architecture integrated with 5G Core — P-CSCF, I-CSCF, S-CSCF, TAS, MGCF, and their interfaces to AMF, SMF, PCF, and UPF.

lesson3 min

SIP protocol basics for telecom

Session Initiation Protocol fundamentals — SIP INVITE, 200 OK, ACK, BYE message structure, header fields, and SDP body for media negotiation.

lesson3 min

P-CSCF, I-CSCF, S-CSCF, TAS, MGCF

Role of each IMS entity — P-CSCF as first contact proxy, I-CSCF for interrogation, S-CSCF as session controller, TAS for telephony services, MGCF for PSTN interworking.

lesson3 min

IMS registration over 5G

Animated call flow — UE sends SIP REGISTER through P-CSCF → I-CSCF → S-CSCF, IMS-AKA authentication challenge, and 200 OK registration response.

animation3 min

Lab: Build IMS + 5GC integrated architecture

Topology exercise — place IMS components (P-CSCF, I-CSCF, S-CSCF, TAS) alongside 5GC NFs (AMF, SMF, UPF, PCF) and connect them with correct interfaces.

lab5 min

Quiz: IMS Architecture

Test your knowledge of IMS components, SIP signaling, CSCF roles, and IMS-5GC integration.

quiz3 min

VoNR Procedures

0/9

Master VoNR call flows — mobile-originated and mobile-terminated setup, dedicated QoS flow (5QI=1), EPS Fallback when NR is unavailable, VoNR-to-VoLTE handover, video calling QoS, and MOS-based call quality analysis.

VoNR call setup — Mobile Originated (MO)

Full MO call flow — SIP INVITE through P-CSCF/S-CSCF/TAS, dedicated QoS flow (5QI=1) via PCF/SMF, media plane through UPF to far end.

animation3 min

VoNR call setup — Mobile Terminated (MT)

Full MT call flow — incoming SIP INVITE at S-CSCF, paging the idle UE through AMF, QoS flow setup, and media path establishment.

animation3 min

QoS for voice: 5QI=1 and dedicated QoS flow

How the dedicated voice QoS flow is established — 5QI=1 parameters (100ms PDB, 10⁻² PER), PCF policy rules, SMF QoS flow, gNB DRB mapping.

lesson3 min

EPS Fallback: when VoNR isn't available

What happens when VoNR is unavailable — NR-to-LTE redirection, IMS re-registration on 4G, and VoLTE call setup as fallback.

animation3 min

VoNR to VoLTE handover during a call

Inter-RAT handover animation — live VoNR call handing over from 5G NR to 4G LTE, bearer mapping, IMS session continuity, and media rerouting.

animation3 min

Video calling over NR

How video calling adds a second QoS flow (5QI=2, 150ms PDB) alongside voice (5QI=1) — dual-flow setup through PCF and SMF.

lesson3 min

Real-world: VoNR call quality troubleshooting

MOS score analysis, jitter, delay, packet loss — diagnosing VoNR quality issues with EVS and AMR-WB codecs.

lesson3 min

Lab: Trace a VoNR call end-to-end

Hands-on exercise — trace a VoNR call from SIP signaling through IMS, QoS flow setup in 5GC, to media path through RAN and UPF.

lab5 min

Quiz: VoNR Procedures

Test your knowledge of VoNR call flows, QoS, EPS Fallback, handover, video calling, and call quality metrics.

quiz3 min