Voice over 5G with IMS : VoNR, EPS Fallback, VoeLTE, RAT Fallback

Course outline : At the start of the deployment of 5G in SA mode, Evolved Packet System Fallback (EPSFB) will be the first solution for the voice service to be deployed since it reuses the VoLTE service. It requires LTE coverage, where 5G coverage is deployed in SA mode. Just as Circuit Switched Fallback (CSFB) was introduced at the beginning of LTE to offer voice service before the advent of VoLTE, EPSFB is an initial solution to offer voice with 5G system before the advent of VoNR. However, the long-term solution for voice with 5G in SA mode is VoNR to unify voice and data services with 5G system.
Apart from VoNR and EPSFB offered with 5G System, it is possible to consider VoeLTE where voice is supported by a 4G access connected to a 5G core network and the IMS (IP Multimedia Subsystem) as well as RAT Fallback where the voice session is transferred from 5G access to 4G access where both radios are connected to the same 5GC core network.
The purpose of this training is to introduce Vo5G with VoNR, VoeLTE, EPS FB and RAT Fallback.

1. 5G Core network and voice over IMS service
1.1. Introduction to 5G core network
1.2. Configuring IMS and SOS DNNs, S-NSSAI and SSC Mode
1.3. UE Route Selection Policy for IMS
1.4. PDU session establishment for IMS and SOS DNN
1.5. LBO Roaming for emergency call and N9HR roaming for non-emergency calls
1.6. Constraints on 5GC/EPC interworking for voice service

2. 5G NSA and VoLTE
2.1. Configuring the NSA option 3X
2.2. Option 3X and VoLTE

3. Solutions for VoIP in the 5G SA context
3.1.1. Vo5G
3.1.1.1. Negotiation between UE and network to use Vo5G
3.1.1.1. Negotiation between UE and 5G RAN to use Vo5G
3.1.1.3. Vo 5G Architectures
3.1.1.4. Registration procedure
3.1.1.5. Call setup procedure
3.1.1.6. 5GS/EPS Interworking for EPSFB
3.1.1.7. RAT Fallback
3.1.1.8. Handover versus Redirection
3.1.1.9. Emergency Services Fallback
3.1.1.10. Audio and video codecs for Vo5G
3.1.2. VoNR
3.1.3. Comparison between VoNR, VoeLTE, EPSFB and RAT Fallback

4. Evolution of DIAMETER Cx, Sh, Rx interfaces towards service interfaces based on the HTTP/2 protocol
4.1. From Cx and Sh to Nhss_ims
4.1.1. Nhss_imsUEContextManagement API
4.1.2. Nhss_imsUESubscriberDataManagement API
4.1.3. Nhss_imsUEAuthentication
4.2. From Rx to Nbsf and Npcf

5. VoNR/EPSFB procedures
5.1.1. IMS Registration/Re-registration/De-registration (same procedure for VoNR and EPSFB)
5.1.3. VoNR Session establishment
5.1.4. EPSFB session establishment
5.1.5. 5G-SRVCC
5.1.6. T-ADS
5.1.7. S-CSCF Restoration
5.1.8. P-CSCF restoration

6. Emergency session
6.1. Emergency session with VoNR
6.2. Emergency session with Emergency Service Fallback
6.3. NG eCall

7. Policy Control for VoNR
7.1.1. Session bidding via BSF function
7.1.2. Reservation of resources for the VoIP session via the PCF function
7.1.2.1. QoS Flows for SIP, RTP audio and RTP video (ViNR)

8. Lawful interception for VoNR
8.1.1. New LI architecture for 5G and for IMS
8.1.2. Lawful interception of target and non-local-ID
8.1.3. from LI S8HR to LI N9HR

9. Evolutions of SIP headers including access information for VoNR, e.g., P-A-N-I.