- T-Mobile and Jio say they achieved a world first in 5G Standalone roaming, with Syniverse handling the interoperability
- The deal supports both 5G SA data and voice – including VoNR, which has historically been no walk in the park
- Early usage suggests 5G SA roaming is already taking a meaningful share of roaming traffic between the two operators
Here’s the thing about cellular roaming. On the one hand, it’s impressive to achieve roaming with 5G Standalone (SA) technology. If it were easy to do, everybody would be doing it, right?
On the other hand, if you’re among the select few who can do 5G SA roaming, you don’t have a lot of roaming partners; therefore, you’re kind of limited in how you use it. C'est la vie.
So it goes for Bellevue, Washington-based T-Mobile and Mumbai, India-based Jio. The two companies declared today that they achieved a world first by enabling 5G SA roaming, thanks to interoperability provided by Syniverse.
5G SA roaming is fully commercial and available now. And interestingly, the deal supports 5G SA data and voice, including Voice over New Radio (VoNR).
Color us surprised, because we’ve been told – including many years ago by former T-Mobile President of Technology Neville Ray – that achieving VoNR is no easy feat.
Actually, Ray’s exact words were: “VoNR is tough” – even for a company like T-Mobile with a lot of experience and a mature network.
That was four years ago, and even though a lot has changed since that time, 5G SA still isn’t a slam dunk. Most 5G operators led with 5G Non-Standalone (NSA), which includes an LTE anchor. According to Ericsson’s Mobility Report, about 390 service providers worldwide have launched commercial 5G services, and of those, just over 90 of them offer 5G SA.
In the U.S., it took AT&T and Verizon considerably longer to deploy nationwide 5G SA than T-Mobile – but as of last year, they declared themselves nationwide with 5G SA. As for 5G voice services? No one was bragging about that right out of the gate, either.
T-Mobile: Voice is more complex
Circling back to present day, Fierce pressed T-Mobile about the challenges surrounding 5G voice and its current roaming achievement.
“Voice services are generally more complex to support than data because they are highly sensitive to latency, mobility and handovers,” T-Mobile Chief Network Officer Ankur Kapoor told Fierce via email.
T-Mobile was able to address these challenges through its converged core 5G standalone deployment, which natively supports both 4G and 5G on the same network infrastructure to help ensure service continuity, he explained.
“That foundation was critical to enabling VoNR. Beyond the typical complexities associated with voice, VoNR was not significantly more complicated than VoLTE for T-Mobile,” he added.
OK, so no big deal, right? Moving on then.
What’s in it for T-Mo, Jio customers?
T-Mobile says this deal with Jio enables T-Mobile customers to experience the same faster speeds, lower latency and more reliable connections when they travel to India and roam on Jio’s 5G SA network.
According to T-Mobile, they’re already seeing meaningful roaming activity in both directions across 4G and 5G SA.
Here are some stats: For T-Mobile customers roaming on Jio’s network, about 28,000 customers used 5G SA roaming in August, compared with approximately 39,500 using 4G roaming. From September 1–15, about 18,100 T-Mobile customers used 5G SA roaming on Jio compared with about 22,900 using 4G roaming.
“For Jio customers roaming on T-Mobile’s network, approximately 14,400 customers used 5G standalone roaming in August, compared with approximately 15,500 using 4G roaming. From September 1–15, approximately 11,200 Jio customers used 5G standalone roaming on T-Mobile, compared with approximately 10,900 using 4G roaming,” according to T-Mobile.
In other words, a significant share of roaming activity between the two operators has already shifted to 5G standalone – roughly 40% to 50% of the combined roaming base during the periods measured, the “un-carrier” said.
Beyond Jio, T-Mobile is open to do 5G SA roaming with other carriers and it’s in discussions with several international operators. “We expect to have additional launches reasonably quickly and invite any mobile network operator that is ready for 5G standalone roaming to engage with us,” according to Kapoor.
Looking at 5G SA stateside
Traditionally, U.S. carriers strike roaming agreements with one another to fill in coverage where their own network doesn’t reach or isn’t adequate. T-Mobile said that once other operators have 5G SA roaming capability, “we will engage with them on potential roaming enablement as well.”
That said, there are challenges in enabling 5G SA roaming between operators.
“5G standalone network architecture is distinctly different from earlier roaming architectures, and enabling it requires integration of new network nodes and services into the roaming environment,” Kapoor said.
Beyond the foundational integration work, operators must carefully manage handoffs from 5G standalone to non-standalone 5G or LTE, including Evolved Packet System (EPS) fallback, as roaming devices may move in and out of standalone coverage.
“Ensuring the right logic, routing and policies are in place to deliver uninterrupted service across multiple generations of network coverage requires detailed planning, testing and engineering coordination between operators,” according to T-Mobile.
To be sure, T-Mobile and Jio are leading the charge when it comes to 5G SA cross-border roaming. With any luck, their peers will catch up before 6G and AI take over the world.
Read more Fierce articles about 5G SA and roaming:
T-Mobile chases voice in 5G - Verizon, AT&T not so much
T-Mobile cites progress in 5G voice, but it's a slog
T-Mobile sure hopes no one notices any difference with 5G VoNR
T-Mobile launches 5G voice in parts of Portland, Salt Lake City