Telecommunications industry runs into problems with 3G mobile network shutdowns

All the talk in Telco Land is about 5G currently, but the older 3G technology from 2001, which telcos would like to move away from, is turning out to be harder to kill than expected, with customer confusion and unhappiness as a result.

Telcos want to re-farm their existing 3G radio frequency spectrum rights for 4G and 5G, but they are struggling to turn off the older networks in an orderly fashion.

It's fair to say that the telecommunications industry has not managed the 3G network closures well, with late, confusing and inadequate communication.

To be fair, it was never going to be easy to migrate from 3G to 4G, two very different technologies, particularly so because the smartphone and mobility revolution meant everyone carries a device nowadays, and the whole thing becomes a gigantic endeavour.

Across the ditch in Australia, the issue has gone so far that the government has stepped in, with Communications Minister Michelle Rowland announcing the setting up of a working group, to help manage the 3G cutover process.

That wouldn't have been necessary if the industry had handled the process better, not leaving some 740,000 phones unable to call 000 emergency services. Even for a much larger market like Australia, that is a substantial number of devices and the problem is serious enough that it may put Telstra and Optus's 3G network shutdowns on hold. 

TPG/Vodafone already pulled the pulled the plug on its 3G network in December.

Technically, the issue is a mix of mobile technology being convoluted and hard to upgrade tidily, along with standards non-compliance by handset makers. 

When 4G networks were first deployed, you may have noticed that your phone switched to 3G when a text message or a phone call arrived. This was a nuisance as it interrupted 4G data transmissions, but it is the way the telco industry decided to do it in the era of per-minute and per-text billing. 

The move to 3G which is circuit-switched like landlines has been complicated by 4G being packet-switched, which is more efficient and similar to how the Internet works.

Initially, although customers had 4G phones, voice, including emergency calls, and texts went over 3G. 

Later revisions of 4G introduced Voice over Long Term Evolution (yes, mobile telco jargon is horrendous), or VoLTE. This had to be supported by both the network, and phones so hardware upgrades on both ends were required.

In theory, that meant telcos could pull the plug on 3G, and put both voice and data over 4G. The reality turned out to very different, however, with a number of showstoppers popping up.

Travellers wanting to roam on to providers overseas found themselves unable to send and receive texts as telcos, like in the United States, switched off 3G, leaving only 4G and 5G service. Older handsets that don't support VoLTE found no 3G network to connect to but even newer 4G phones had problems overseas.

Some not-so-old phones support 4G VoLTE, but not VoLTE Roaming. That is, even if your home network operator had signed a deal to roam on 4G everywhere overseas, and this wasn't guaranteed, you still had no cellular calls and texts in some countries. Without VoLTE Roaming support, the phone would drop down to 3G.

That probably saved a good amount in call roaming charges for customers, but it meant for example two-factor authentication texts didn't make it through.

Minister Rowland's announcement talked about some 4G phones with VoLTE support being configured to make emergency calls on 3G. At first this seems odd, because why would you drop down to the older network if 4G is available?

Turns out that manufacturers were the cause of that. From the telco industry standards body, the Global System for Mobile Communications Association which is abbreviated GSMA and not GSMCA for some reason (thanks to Steve Biddle for spotting this):

"Initially, to gauge the extent of the problem, the GSMA investigated the issues and carried out a poll among UE vendors. The insights showed that devices were a mix of compliant and non-compliant with the 3GPP VoLTE Emergency Call specifications that already exist, which state that VoLTE Emergency Calls are distinct and separate from “normal” VoLTE.

So, a device should always attempt to initiate an emergency call (either via circuit-switch or packet-switch technology, dependent on local network capability) irrespective of whether a normal voice service is available."

For telco subscribers, this is a very difficult issue to spot as most people assume their 4G phone works as advertised and few are able to test if the device is compliant with 3GPP specifications.

That such phones were allowed to be sold at all, in an increasingly landline-less world with 3G shutting down, and where the mobile is the device people rely on by default to make emergency calls, points to shortcuts being taken by the telco industry.

Current telco employees can take some solace in 4G having a very long shelf-life, with the technology being cost-effective and performing well enough to be around for at least another decade, possibly longer, until 6G starts to appear.

New Zealand also shutting down 3G

Meanwhile, we're also moving into a future without 3G with all the complications that brings. As a related aside, it's not just smartphones that risk being stranded, but other 3G connected devices. The Australian Mobile Telecommunications Association (AMTA) lists:

• EFTPOS terminals
• Industrial routers
• Scanners
• Security monitoring
• Telematics
• Asset Tracking
• Environment monitoring

... along with medical alarms and home security devices. Some older wearables, like Apple Watch 3, 4 and 5 and Samsung Galaxy Watch and Watch Active 2 won't work everywhere on 4G.

One New Zealand is sunsetting its 3G network by August this year, and spokesperson Matt Flood said it is really important for the telco not to leave customers behind when it happens.

As for the issues across the Tasman, Flood said New Zealand won't face the same problems that Australia does.

"We’ve looked into this - the specific issue in Australia relates to 4G VoLTE handsets configured to use 3G to call emergency services. We don’t face the same issue here. On One NZ, all approved 4G VoLTE devices on our network are configured at a device level to try to use 4G to contact emergency services," Flood said.

Customers who still have 3G and non-VoLTE capable devices on One NZ's network will be contacted starting next week, to inform them of their options and giving them plenty of time to upgrade ahead of the 3G shutdown.

"Before switching off our 3G network we’ll have rolled out 4G or 5G to everywhere currently served by 3G, and by switching off 3G we can then repurpose the radio spectrum to benefit our customers," Flood said.

Spark told interest.co.nz that it will close down its 3G network later than One NZ, towards the end of 2025.

"Our 3G network primarily operates on a limited low band spectrum (850MHz), which is required to further increase 5G services in rural Aotearoa. This is because it has greater range and penetration compared to other spectrums," Spark spokesperson Sam Smith said.

Like One NZ, Spark still has customers with phones that rely on 3G for some functionality, around two five per cent. With approximately 2.7 million customers, that amounts to around 54,000 135,000 customers on Spark who need to replace their devices.

However, some 4G phones could try to switch to 3G for calls, Smith explained.

"Some older device models can’t make voice calls over 4G (VoLTE) and so they fall back to 3G when calls are made. This is predominantly due to the age of the device – for example, an iPhone 6 is not VoLTE capable on Spark’s network," Smith said.

"Other customers may have the capability on their phone but need to enable it in their settings, or they may have purchased a phone overseas or from organised importers that is not compatible with the spectrum much of our 4G network operates in," she added.

Spark said it has contacted customers who still use 3G reliant devices on the telco's personal, business and IoT plans when it made the network shutdown announcement.

The telco will continue to do so, and supports the New Zealand industry association, the Telecommunications Forum (TCF) to deliver further educational resources on the issue.

TCF chief executive Paul Brislen noted that customers who still use 3G-only devices will need to upgrade them, before the networks are switched off.

"If customers are unsure as to whether this change affects them, they should contact their network provider directly for the most up-to-date information," Brislen said.

2 Degrees also intends to shut down its 3G network towards the end of 2025, and has published information for customers.

Update One NZ has moved the date for switching off 3G - and 2G - from August this year to "calendar year 2025", a presentation by chief executive Jason Paris stated.

Further technical information received on the reason why some 4G handsets switch to 3G for emergency calls say this is how the older 3GPP Release 8 standard handled them. The standard was "frozen" in 2008, and meant that emergency calls to 111 in New Zealand, 000 in Australia and 911 in the United States were forced to 3G. Release 8 devices are often older than 8 years by now.

Some Release 8 devices will force all calls to 3G, which users will be able identify. The problem is with other Release 8 devices on which normal calls will work fine over 4G, but emergency calls will fail if there is no 3G network available. Users may not be aware of this until they need to make an emergency call. 

Ahead of the 3G network shutdowns, mobile network operators in Australia are trying to identify Release 8 devices, and tell users to change out to newer handsets. Grey import phones complicate this identification process, as they adhere to different regulations and standards across various markets.

Update March 22 2024 Spark said the two per cent estimate is wrong, and the number of customers affected is actually around five per cent.