According to the Cailian News, in the China 5G enhanced technology R&D trial organized by the IMT-2020 (5G) promotion group, Huawei used the Mate 20X 5G mobile phone to open the world's first VoNR call under the 5G SA network, including voice and video. . VoNR is the basic voice solution under the 5GSA network architecture. This call is based on the 5G network built by Huawei under the IMT-2020 (5G) promotion group. The two mobile phones are located more than 60 kilometers apart.
VoNR is one of the target voice solutions for 5G networks. According to ZTE's website, the 5GC core network supports IMS-based voice solutions. In order to meet the characteristics and requirements of IMS services, 5GC introduces the following features:
1. Qos guarantee of speech stream: 5GC Qos architecture provides special 5GC parameter values, and optimizes IMS speech quality.
2. EPS fallback: When the UE does not support Vo5G, the network end supports the provision of voice fallback to the E-UTRA function. The UE may hand over 4G and use VoLTE's voice service. The solution requires 4G-G interoperability and is based on the 4G-5G interoperability architecture. Therefore, a converged EPC-5 GC N interface and an N 26 interface are required to support voice continuity.
3. Paging strategy optimized for IMS services.
4. The network notifies UE, through the functions and information of IMS, including: AMF provides UE instructions supported by IMS through PS sessions, and SMF provides P-CSF addresses to UE during the establishment of PDU sessions.
5. The domain selection of the original session/ call of the UE, and the selection of the end domain of the IMS voice.
The solution helps operators deploy IMS voice solutions carried by 5G and achieve smooth handover between VoLTE and VoNR. The solution supports the reuse of IMS investments in the VoLTE construction process and the 4GNG voice experience consistency through a unified IMS network.
To put it simply, there are two options for 5G calls. The first is that VoNR, is another EPS fallback,fallback that is similar to the 4G era CS fallback, voice fallback technology. If the VoNR scheme is adopted, VoNR can realize the concurrency of voice service and data service through the deployment of IMS,. All the services are carried through 5G network, but the voice service needs IMS for service control.
EPS fallback can continue to “split” into VoLTE and CSFB, which are not described here.