Five years ago, BT became the first UK telco to launch 5G via its EE brand. But this now-ageing generation of mobile technology, it is fair to say, has been hobbled ever since by its continued reliance on 4G. Non-standalone 5G, the version BT and most other telcos worldwide have deployed, introduced a new radio (imaginatively christened 5G New Radio) but tethered this technological racehorse to the old donkey of the existing 4G core. This week, across 15 of the UK's biggest cities and towns, BT powered up a standalone successor that ditches the donkey.

Previously dubbed "real" 5G, by some in the industry, it takes advantage of new core network features provided, in BT's case, by Ericsson. Customers of the service should benefit from higher-speed connections and lower latency, a measure in milliseconds of the roundtrip journey time for a signal across the network. The launch intriguingly comes days before Apple is expected to give an update on standalone and artificial intelligence. In the future, BT's network could theoretically support applications on iPhones and other advanced handsets that would simply not work on non-standalone 5G. Customers, it hopes, will pay a premium.

But this will depend on how well BT can market the service, and whether people are prepared to pay more for an upgraded network. History, by contrast, shows that average revenue per user has tended to fall as telcos have cycled through new generations of technology. "Given the industry's enduring struggles to monetize investment, EE's decision to charge a premium for 5G standalone is laudable," said Kester Mann, an analyst with CCS Insight, by email. "However, I question how long EE will be able to maintain it given that rivals Vodafone and Virgin Media O2 are already offering the technology for no extra charge."

Banding together

Yet while BT did not beat its competitors to standalone, it can boast what appears to be a more widely available service, covering an area of 18 million people at launch. The network upgrade has not been straightforward. "We had to do work at each radio site to get it ready," said Howard Watson, BT's chief security and networks officer, during a presentation at BT's headquarters. Across 30,000 cells, his team's job has involved allocating portions of spectrum in the 700MHz, 1800MHz, 2100MHz, 2600MHz and 3.5GHz bands to standalone while ensuring there is enough left for the 4G and non-standalone services that most customers still use.

Only by combining bands can BT ensure the standalone service is superior to non-standalone, and waiting for the technology to support this "carrier aggregation" partly explains why the telco has not launched until now. "I'm not saying we're launching across all cities with five carriers aggregated," Watson told Light Reading. "At each site we deploy the right number of carriers for the demand at that location. But yes, the devices that are out or coming out have that ability to give better performance."

The cities and towns where services are now available do, of course, map to some of the most densely populated zones. But they are also places where BT claims to offer 5G network coverage of at least 95%, and in most cases about 98%. It has avoided areas still served by Huawei, the Chinese vendor whose equipment it must remove, under government orders, by the end of 2027.

"Clearly, we have not launched 5G standalone on our Huawei infrastructure because we are replacing that," said Watson. Relatively few 5G sites are now served by the Chinese manufacturer, although it figures more prominently in BT's 4G network. "We had to make sure that we had sufficient volume of Ericsson and Nokia sites," Watson explained, referring to BT's two other radio access network (RAN) suppliers. "It was important for us to make sure that we had that really reliable outdoor coverage because we felt not everyone does that."

From a customer perspective, one of the most noticeable improvements could be indoor coverage, hampered on non-standalone connections by BT's use of 1800MHz spectrum, which penetrates walls less effectively than sub-1GHz frequencies do. "Today, on non-standalone, you have to connect via a 4G network to get the control plane working," said Watson. "That's on 1800MHz in our network, which has limited indoor coverage, and now you can get the control plane and user plane over 700MHz, so you are going to get improved indoor coverage."

Because standalone does not have to piggyback on the 4G core, latency is also expected to be somewhat lower than it is for non-standalone customers. This may hold limited appeal for most users today, but it may be an important need for emerging applications linked to artificial intelligence.

Huawei ditched

Perhaps the hardest task on the network side has been the transition to a new core. The old 4G one, which came with BT's £12.5 billion (US$16.5 billion, at today's exchange rate) takeover of EE in 2016, was provided by Huawei. It was finally ditched earlier this year after BT finished migrating customers to a new converged core – able to support 4G, non-standalone and standalone 5G services – provided by Ericsson. The process has involved 200 million individual migrations, Watson told reporters.

The alternative would have been to roll out a separate 5G standalone core, he later explained to Light Reading. "As you migrated from our 4G evolved packet core with 5G control plane capabilities, we could have pushed you onto a new core, but we just felt that was an inefficient use of infrastructure, and so pushing Ericsson to have that dual-capability 5G core was important for us," he said.

Rather than executing a like-for-like swap, he has sought to improve the network each time BT has replaced a Huawei component. Just as more capacity has been added to the RAN, so the core has been given a major technological upgrade with the shift to 5G standalone. Ericsson's technology sits on a telco cloud built with support from Canonical, a UK software company. The control plane, the decision maker in the network, is distributed across eight sites, while the user plane, the network's traffic cop, extends across 16.

All this should help to make 5G standalone an ideal platform for artificial intelligence in the network, reckons Watson. "This has come together at quite an opportune moment, because AI is clearly quite compute-intensive," he said. "Increasingly, there will be compute for workloads in the network and I now have the ability to place those where the workloads demand using that network cloud infrastructure. I think that's a real benefit of the network platform that will deliver value over the next few years."

Will customers bite?

Arguably the most challenging job of all falls not to Watson and his team but to BT's commercial arm. Educating consumers about 5G standalone, and why they should care, will not be easy. New gadgets and SIMs are needed, and most BT customers will not currently own compatible handsets. BT is advertising a TCL 50 smartphone, available for £48.33 a month on a three-year plan, as well as the Samsung GS24, costing £62.81 a month over the same period. But iPhone support will be crucial.

"The elephant in the room for EE is device compatibility," said Mann. "Significantly, Apple has yet to provision 5G standalone on iPhones for UK mobile networks, forming a major barrier to adoption. Many eyes at EE HQ will therefore be glued to Apple's announcements next week when it unveils the iPhone 16."

There is also the problem of straying outside the standalone coverage area and losing high-speed connectivity. To overcome that, BT will provide standalone customers with a feature called Network Boost, which uses a 3GPP-standardized technology to supercharge the 4G connection in cities where 5G standalone currently remains unavailable. But it won't, of course, be as good.

There was little talk this week of network slicing, a ballyhooed feature of standalone that reserves a part of the network for applications or customers needing higher throughput, lower latency or other service guarantees. That could bring further opportunities to monetize the network if telcos get it right. How customers react to the initial standalone launch will be critical.