T-Mobile has deployed commercial Voice over 5G (VoNR, or Voice Over (5G) New Radio) service in limited areas of Portland, Oregon and Salt Lake City, Utah. The Un-carrier plans to expand VoNR to many more areas this year. Now that Standalone 5G (5G SA) is beginning to carry voice traffic with the launch of VoNR, other real 5G services, such as network slicing and security are likely to be deployed. T-Mobile customers with Samsung Galaxy S21 5G smartphones can take advantage of VoNR today in select areas.
“We don’t just have the leading 5G network in the country. T-Mobile is setting the pace for providers around the globe as we push the industry forward – now starting to roll out another critical service over 5G,” said Neville Ray, President of Technology at T-Mobile. “5G is already driving new levels of engagement, transforming how our customers use their smartphones and bringing unprecedented connectivity to areas that desperately need it. And it’s just going to get better thanks to the incredible T-Mobile team and our partners who are tirelessly innovating and advancing the capabilities of 5G every day.”
Standalone 5G removes the need for an underlying 4G LTE network and 4G core, so 5G can reach its true potential. In other words, it’s “pure 5G”, and T-Mobile was the first in the world to deliver it nationwide nearly two years ago.
The addition of VoNR takes T-Mobile’s standalone 5G network to the next level by enabling it to carry voice calls, keeping customers seamlessly connected to 5G. In the near-term, customers connected to VoNR will notice slightly faster call set-up times, meaning less delay between the time they dial a number and when the phone starts ringing. But VoNR is not just about a better calling experience. Most importantly, VoNR brings T-Mobile one step closer to truly unleashing its standalone 5G network because it enables advanced capabilities like network slicing that rely on a continuous connection to a 5G core.
“VoNR represents the next step in the 5G maturity journey-an application that exists and operates in a complete end-to-end 5G environment,” says Jason Leigh, research manager, 5G & Mobility at IDC. “Migrating to VoNR will be a key factor in developing new immersive app experiences that need to tap into the full bandwidth, latency and density benefits offered by a 5G standalone network.”
“The commercial launch of the VoNR service is another important step in T-Mobile’s successful 5G deployment,” said Fredrik Jejdling, Executive Vice President and Head of Business Area Networks at Ericsson. “It demonstrates how we as partners can introduce 5G voice based on the Ericsson solution.”
“We are proud of our partnership with T-Mobile to bring the full capabilities of 5G to customers in the United States,” said Tommi Uitto, President, Nokia Mobile Networks. “Nokia’s radio and core solutions power T-Mobile’s 5G standalone network – and this VoNR deployment is a critical step forward for the new 5G voice ecosystem.”
“At Samsung, we want to give our users the best possible 5G experience on every device – and today’s announcement represents a big step forward,” said Jude Buckley, Executive Vice President, Mobile eXperience at Samsung Electronics America. “By supporting extensive integration and testing, and working alongside an industry leader like T-Mobile, we’re bringing to life all the benefits of 5G technology with the help of our Samsung Galaxy devices.”
VoNR is available for customers in parts of Portland, Ore. and Salt Lake City with the Samsung Galaxy S21 5G and is expected to expand to more areas and more 5G smartphones this year including the Galaxy S22.
T-Mobile is the U.S. leader in 5G with the country’s largest, fastest and most reliable 5G network. The Un-carrier’s Extended Range 5G covers nearly everyone in the country – 315 million people across 1.8 million square miles. 225 million people nationwide are covered with super-fast Ultra Capacity 5G, and T-Mobile expects to cover 260 million in 2022 and 300 million next year.
Voice Over NR Network Architecture:
Voice Over NR network Architecture is consist of 5G RAN, 5G Core and IMS network. A high level architecture is shown below. (Only major network functions are included). This network architecture supports Service based interface using HTPP protocol.
VoNR Key Pointers:
- VoNR rely upon IP Multimedia Subsystem (IMS) to manage the setup, maintenance and release or voice call connections.
- UE PDCP should support RTP and RTCP, RoHC compression and MAC layer should support DRX
- SIP is used for signaling procedures between the UE and IMS.
- VoNR uses a QoS Flow with 5QI= 5 for SIP signaling messages and QoS Flow with 5QI= 1
- QoS Flows with 5QI= 5 is non-GBR but should be treated with high priority to ensure that SIP signaling procedures are completed with minimal latency and high reliability.
- QoS Flow with 5QI= 1 is GBR. This QoS Flow is used to transfer the speech packets after connection establishment
- gNB uses RLC-AM mode DRB for SIP signaling and RLC-UM mode for Voice Traffic (RTP) DRBs
- 3GPP has recommended ‘Enhanced Voice Services’ (EVS) codecs for 5G
- EVS codec supports a range of sampling frequencies to capture a range of audio bandwidths.
- These sampling frequencies are categorized as Narrowband, Wideband, Super Wideband and Full band.
- VoNR UE provides capability information during the NAS: Registration procedure with IE ‘ UE’s Usage Setting’ indicates that the higher layers of the UE support the IMS Voice service.
- The AMF can use the UE Capability Request to get UE’s support for IMS Voice services. gNB can get UE Capability with RRC: UE Capability Enquiry and UE Capability response to the UE. The UE indicates its support for IMS voice service with following IEs
- ims-VoiceOverNR-FR1-r15: This field indicates whether the UE supports IMS voice over NR FR1
- ims-VoiceOverNR-FR2-r15: This field indicates whether the UE supports IMS voice over NR FR2
- within feature set support IE ims-Parameters: ims-ParametersFRX-Diff, voiceOverNR : supported