2G Or Not 2G, That Is The Question

Since the very early 1990s, we have become used to ubiquitous digital mobile phone coverage for both voice and data. Such has been their success that they have for many users entirely supplanted the landline phone, and increasingly their voice functionality has become secondary to their provision of an always-on internet connection. With the 5G connections that are now the pinnacle of mobile connectivity we’re on the fourth generation of digital networks, with the earlier so-called “1G” networks using an analogue connection being the first. As consumers have over time migrated to the newer and faster mobile network standards then, the usage of the older versions has reduced to the point at which carriers are starting to turn them off. Those 2G networks from the 1990s and the 2000s-era 3G networks which supplanted them are now expensive to maintain, consuming energy and RF spectrum as they do, while generating precious little customer revenue.

Tech From When Any Phone That Wasn’t A Brick Was Cool

A 1990s Motorola phone
If this is your phone, you may be in trouble. Digitalsignal, CC BY-SA 3.0.

All this sounds like a natural progression of technology which might raise few concerns, in the same way that nobody really noticed the final demise of the old analogue systems. There should be little fuss at the 2G and 3G turn-off. But the success of these networks seems to in this case be their undoing, as despite their shutdown being on the cards now for years, there remain many devices still using them.

There can’t be many consumers still using an early-2000s Motorola Flip as their daily driver, but the proliferation of remotely connected IoT devices means that there are still many millions of 2G and 3G modems using those networks. This presents a major problem for network operators, utilities, and other industrial customers, and raises one or two questions here at Hackaday which we’re wondering whether our readers could shed some light on. Who is still using, or trying to use, 2G and 3G networks, why do they have to be turned off in the first place, and what if any alternatives are there when no 4G or 5G coverage is available?

How Big Is The Problem And Where Can We Go From Here?

The Android mobile network settings screen on a 2-SIM phone, with both set to 2G only.
I shouldn’t be surprised that I get a far better 2G signal where this is being written than I do 4G or 5G.

The first question finds its answer fairly easily, before we’ve even considered IoT devices. Take a journey away from the cities and main transport arteries, and it’s likely you won’t have to go far before the faster connections stop and 2G is your only option.

Data rates drop to levels from the dial-up age with GPRS and EDGE, and any electronic devices you own with a speaker start that characteristic 2G chirping as they pick up stray RF from your phone. Speaking from a European perspective this happens even in places one might consider well populated, for example when a Eurostar train travels through the Belgian countryside.

Aside from the convenience of rural mobile phone users, there are plenty more places where older tech can be found. In the estimated 7 million British smart meters which will go offline after the turnoff for example, or in the numerous anecdotes of cars with online systems behaving strangely when they lose their cellular connection. But beyond that we have several decades of devices of all kinds that use a cellular connection, while many will like those smart meters be owned by utilities or public bodies, countless more will be in private hands. When the cell service they rely on stops it’s likely many owners will only become aware when the device they rely on ceases to work. A quick online search finds plenty of inexpensive devices still on sale with 2G connectivity, so it’s not even a legacy issue.

A GSM module on a development board
These ubiquitous GSM modules have made cellular IoT devices easy, but they could be about to bring a huge headache. Aseel zm, CC BY-SA 4.0.

So if the older networks are still required in some form, just why are they being turned off? Here the argument is mostly economic, despite those rural travelers and IoT devices, it’s no longer economic for the carriers. The older technologies still occupy a significant quantity of valuable spectrum, and the infrastructure running them is power-hungry for little revenue. A remote sensor with a 2G SIM in it uses a tiny quantity of data, nowhere near enough to pay for the network it uses.

As to alternatives, the easy answer is that every device should simply upgrade to 4G or 5G, though we expect the scale of the task would make that impossible in anything but a very long timescale, and even then the costs could be difficult to bear. Can it be kept then?

At the network end we have a question for any readers who work in the industry, if the 2G network is vital but has such limited use, is it possible to maintain a 2G network shared by carriers on a very small piece of shared spectrum? We know that a 2G implementation using SDR technology is a fraction of the size and power consumption of the large cabinet-sized base stations which went in when GSM was a new technology, could such a network of low-bandwidth 2G cells provide just enough to keep all those smart meters and other devices working?

Can You Take A Little Bit Of The Network With You?

A woman leaning out of a window to get a phone signal, with the caption 'Boost your mobile signal at home with Vodafone Sure Signal'.
A 2010 advert for Vodafone’s now-discontinued femtocell product.

This neatly brings us to the measures a Hackaday reader might be able to take themselves. A femtocell is a very small scale mobile phone cell sometimes used by networks to fill in small gaps in coverage, but it is also something that can be found in a domestic setting both as a commercial product and from a hacker perspective. The commercial home femtocells are largely obsolete because most phones now offer Wi-Fi calling, but they usually take the form of a box similar to a home router that would create a short-range cell using the home broadband connection as a backhaul. During the 3G era they were sold by carriers as a home upgrade, but at least where this is being written the service has largely been switched off. It’s possible that these technologies could return to be used in some situations, but they would require carrier buy-in.

All isn’t lost for the more adventurous souls though, because 2G networks have for quite some years been an open book in terms of the way they work. With a relatively inexpensive SDR and open source software such as Osmocom or OpenBTS it’s possible to host your own 2G cellular network giving internet connectivity back to your devices with no carrier involved. We feel duty bound at this point to remind you that most countries take a dim view of unlicensed spectrum usage.

From reading up on the tale of 2G and 3G switch-off in both the countries that have done it, and those that intend to do it, the overall impression is of a seamless operation for the majority of people who long ago switched to 4G or 5G without noticing, but something of a headache for rural users and owners of 2G-connected IoT devices. It appears that 2G in particular is one of those technologies which gained so much traction that we seem doomed never to be rid of it.

Header image: Luis, CC BY-SA 4.0.

66 thoughts on “2G Or Not 2G, That Is The Question

  1. Wasn’t LTE supposed to be agile to carve out bits of spectrum so a single GSM carrier could be kept on the air without “costing” too much LTE bandwidth?

    Seems to me that even GSM had the ability to allocate timeslots, and if there are few devices, then few timeslots should be carrying GSM-type frames. The rest of that airtime should be able to carry 5G or 6G or whatever frames, if they’d designed those newer protocols to work with, rather than displace, those millions of legacy devices.

      1. Yes they are, actually. So what you do is “preallocate” Resource Blocks (RB’s) in a segment of the overall carrier, these are on a 270kHz wide slot. This reserves space for a 2G carrier.
        Then the basestation synthesises the 2G carrier and mingles it in.
        The difficulties are more in the linearity of the PA amplifying the composite signal as the 2G component has a markedly different linearity characteristic, and avoiding intermodulation products. Also we must make sure the 2G carrier phase is well respected, or else it might create problems with SACCH etc. But, I think it’s do-able.

        Any 2G MS’s should ignore the 4/5G “mush” and still find the 2G component peeking out.

  2. So, you still have 3G? Shut down here a few years back, with 2G likely not being far behind, even though telecom wants to keep it “alive” for IoT (2G bandwidth has been narrowed considerably, now to the point of being unusable).

  3. Thanks to the 2G/3G shutdown the Toyota Drive Connect system in my 2013 4runner is no longer working. What was once a touted safety feature is now a worthless button in my headliner.

    1. The license for ISM is on the manufacturer of the device instead of for example: you.
      I think that some of the ham band is sharing with GSM (in the USA).
      Tl:dr there needs to be a licence to broadcast radio somewhere in the chain.

      1. ISM bands are “free for all” because they’re harmonic multiples of some legacy military radar etc. systems that can’t be allocated to anyone because you can expect interference at any time. There’s rules that you should follow transmit duty cycle limits and power limits, and you can’t sell devices that violate these, but otherwise you don’t need a license to broadcast.

    2. Sadly neither the 900 MHz and 868 MHz license free bands are wide enough.

      USA 900 MHz band is 902 – 928 MHz
      For GSM900 the frequencies used are:
      880 – 915 MHz for uplink from phone to base station.
      925 – 960 MHz for downlink from base station to phone.
      If you go “Ha! Slices of both fit the licence free band!” you’d be technically correct.
      But the uplink/downlink are paired and use a 45 MHz split.
      So a base station shoehorned into the 925 – 928 MHz slice would be listening to handsets transmitting on 880 – 883 MHz. And that is very much not license free.

      The SRD860 band in Europe and elsewhere is usually around 863 – 870 MHz.
      So when GSM850 uses these frequencies:
      824.2 – 848.8 MHz for phone to base station uplink.
      869.2 – 893.8 MHz for base station to phone downlink.

      So only the tiny 869.2 – 870 MHz slice matches even part of the band.
      And the paired uplink is also 45 MHz below that at 824.2 to 825 MHz, once again not license free.

      Making it work on the USA band would require using a nonstandard split like 25 MHz.
      And there is no guarantee that any phone would tolerate operating like that.
      Or building a receive converter that converts 2400 MHz ISM band or 1296 MHz ham band to 947 – 960 MHz for the phone to receive.
      But now it is no longer using normal, stock, off-the-shelf GSM capable phones.
      Could still be a fine project to do. Especially with some older phones with easily available service manuals.

      1. You forget about “the law to listen”.
        In fact You need two separate devices. ISM transmitter that fits into ISM allowed frequency [checked] and separate non-ISM receiver that fits within that 45Mhz frequency offset. Something like SDR dongle may do it. And You don’t need any paperwork for the receiver part. Just prove that SDR can’t transmit will make it legal in any band.

    3. At some point, a few channels of the GSM900band should be made license-free, with the restriction that they can only be used for femtocells and with a transmit power limit. The rest of the band should be reallocated for other purposes.

      We could then buy femtocells that would convert 4G/5G/Ethernet to 2G/3G. The femtocell would be shipped with a few SIM cards to insert in the devices that need to be connected

  4. 2G is still relevant as a fall-back.
    There are so many forgotten systems that may rely on it.
    Emergency phones in places like elevators or at the roadside.
    Embedded systems which send warning messages via SMS etc.

    I know that resources are scarce, especially frequency allocations.
    But there’s a point at which reason must win over progress.

    The basic infrastructure must be kept intact, because we depend so much on it.

    It’s also a different application, maybe.
    2G systems like GSM use lower frequencies and have a wider coverage.
    The individual cells can be bigger/wider apart to each others, too.

    Being simple, 2G can work under difficult situations.
    That’s why I think that the basic 2G functionality, SMS at least, should be remained.

    1. A 2G network doesn’t necessarily have the SMS available, since it’s a separate system. On the other hand, 4G and 5G can support the same service just fine.

      The use of lower frequencies is a matter of frequency allocation. 5G networks can operate as low as 600 MHz, although your phone might not. The 700 to 900 MHz bands can be used for wide area cell coverage if these frequencies become available. Access will be slow though.

      1. Although, I’ve tried to use SMS over NB-IoT/CatM1 and it doesn’t seem to work as well. The message queue rotation seems to be handled differently and it may take a day or so to get anything through.

  5. The last 3G supplier is shutting down at the end of June In Australia. I still use my Nokia 6120 phone on the 3G network as my daily phone. Now 16 years old and, noone will believe this, still get a week between having to charge the battery !

    1. I’m another Aussie still using a 3G phone (2G has already been long dead here), 15 years old and also still with a good battery (although I refuse to use a mobile phone except for emergencies, and now SMS 3FA codes, so it’s turned off 99% of the time). Coles have cheap Telstra/Optus “Lite” model dumb phones on special at the moment so I’m going to get one of them as a 4G-capable replacement.

      At first 4G was implemented only at much higher frequencies (1800MHz, or higher) than 3G in Australia, but telcos later rolled out 4G on a lower 700MHz band. The catch is that earlier devices (even those sold by the telcos themselves) may only support the original higher frequencies on 4G. So you might have a good 4G device made in the early/mid 2010s, but it might not have the coverage of a newer device once 3G is switched off.


      Add to that the requirement that phones support VoLTE in order that voice calls still work, and it really is a minefield if looking for second-hand phones, or trying to make sure that one’s current phone will still function adequately after the 3G switch-off.

      A whole lot of e-waste set to be generated just to keep on doing the exact same thing. But that’s nothing new. I see that HackADay comments won’t work in Links or Dillo now either, so more e-waste generated by people who need to buy new computers powerful enough to run Javascript-supporting web browsers so they can get their HaD commenting fix from any device. I’ll just make this my last comment here instead.

      Sent via a 4G mobile broadband modem (my home internet connection) that doesn’t support the new 700MHz 4G band and is therefore still intermittently dropping back to 3G when the 4G signal falters.

    2. I took my old Samsung smartphone off the network, and it gets a week of battery now.

      It would be technically possible to drop newer phones down to Cat M1 operation, which still supports voice and slow data rates with minimal energy use, but I doubt anyone actually makes phones that can do that to save battery. It’s mainly intended as a 2G replacement for IoT devices.

      1. I work for a remote patient monitoring company that uses cellular connected medical devices for older less tech-savvy patients in rural areas.

        Although most have a lte-m signal at their home, our devices fall back to 2G in about 10% of cases when they don’t have any LTE signal. The 2G shutoff will be a significant issue for rural and tribal patients for us and we have been looking into other solutions.

        1. There seems to be problems in the way LTE-M signals propagate to indoors environments, but I think it has to do with the higher frequencies used, since 2G is squatting the lower frequency spectrum. Same thing for wide area coverage. These problems should go away if they can free the frequencies for LTE use, and they pretty much have to at some point because you just can’t get 4G/5G coverage economically otherwise – you’d have to pepper the landscape with cell towers.

    1. With that logic removing payphones should be forbidden.

      I work for a bus company. We have had 15 complaints about a bus stop being removed, even though our checkin data showed that only 7 passengers travelled from or to that stop in a year.

    2. Yep. 850 MHz or 900 MHz GSM is the lowest common deminator when it comes to cellular standards.
      In my opinnion there should be some GSM coverage everywhere with cellular service due to that.
      Essentially EVERY phone made in the last 20 years in that or nearby region could then make emergency calls.

  6. (my reply is not showing up. If this is now doubled up, I apologise)
    The last supplier of the 3G network throughout Australia is shutting down at the end of June next year. This will leave massive black spot holes throughout the country where 4g and 5g do not yet cover the older 3g areas.
    I still use my 16 year old Nokia 6120 phone daily on the 3G network.

    1. I live in suburban Canberra (that’s the capital city of Australia for international readers) and I have an email from Telstra (our national carrier, who advertise having the “widest coverage” here) saying that when 3G is shut down my phone won’t work in my house. Also that they have no plans to fix this. They should be sent a bill for all the e-waste they are about to create.

  7. With the analog cellphone shutdown in 2009, older GM OnStar service went buh-bye. Only some of the last models with analog systems had digital upgrades made available.

    The old OnStar systems used a Motorola bagphone module connected to a modem box which had a separate, plug in GPS receiver. The GPS modules can be pulled out and used as standalone receivers but they speak RS-422 or RS-485 so if your host only does RS-232 that needs converted. Also, the OnStar boxes didn’t do NMEA formatted GPS data. Fortunately the GPS modules can be switched to output that.

    So if you’re digging around junkyards with circa 2009 and earlier GM vehicles, see if you can get the OnStar phone and modem box for a cheap price or nothing. They’re completely useless to have in a working vehicle so the yard *shouldn’t* expect to get much out of them.

  8. Some 4G smatphones can only use 4G network for data and not phone calls. For phone calls the use 2G and 3G networks. So even a four year old smartphone it’s affected if both 2G and 3G network are switched off.

    Switch off of analog networks was almost seamless because for a long time the cellphones were rented, so it was simply a question to give a new apparatus. I remember that at least three analog system were used 160 MHz, 450 MHz and 900 MHz. Besides the users og 160 and 450 MHz phone were very few. 900 MHz had more success but because the 2G network had better performances and one could find cheaper plans compared to ETACS phones, people rapidly changed system by themselves. And because cellphones were used as mobile phone, one telco decied to give a 2G phone for free to the last ETACS phone users.

    Now there are way more 2G systems that aren’t used as phone but as M2M systems and are everywhere, so it’ impossible for the telco to give a free 5G phone in substitution.

  9. I’ll skip a lot of the relevant facts to say that for the technical question of providing simple devices with small amounts of data today, I would expect to prefer narrowband modern standards rather than the older ones, although I might try and pick a lower band to use for the purpose when you’re worried about range. NB-IoT, LTE Cat M, that kind of thing.

    Generally with anything radio, we have a long list of things that we know from a scientific perspective could improve the performance. Some things are about the signal and some are about the coding and such, which faster processors can chug thru better. Over time we finally get hardware/software support for more of those tactics, depending which ones someone decides are worth implementing. So while some of the changes in newer cell networks cater to bringing more bandwidth per area by smaller cell sizes that don’t have to have good range, a narrowband signal on a low enough band out of the available options could still improve range. Some of the mid-UHF frequencies that form the lowest available for regular cell phones aren’t bad bands overall, even if they don’t blanket the hills like a VHF radio does.

  10. One thing that isn’t mentioned is how many fewer masts 2G needs to 5G – a 2G mast can serve a very wide area and for rural areas that is rather required – way too expensive and destructive to put up masts every few hundred meters across nations.

    Same thing with radio stations, the old ones can be heard in some cases way beyond a nations borders and rarely go dead for geography while the admittedly very nice to use DAB stuff can be snuffed out rather easily.

    For me both should remain, and perhaps even be picked up as a public service – reliable and useful to a wide population just not great a making profits in the high speed internet age…

      1. Depends. For very few connected customers, maybe, because you’re allowed to use more TX power from the handset. Once the number of customers goes up though, the cell becomes saturated.

        A GSM cell can reach up to 35 km or 3900 square kilometers around the tower. One cell so far as I can make out can support 992 simultaneous calls, or about 0.3 people per square kilometer at maximum cell size. Even sparsely populated areas can easily have 10 people per square kilometer, so it gets crowded too easily. 4G can split the cell into sectors and support 10-20 times as many subscribers, so the practical cell size can be larger.

  11. My “early-2000s Motorola Flip” is the best phone I ever owned. Everything since has fallen short in its fundamental duty – make clear phone calls. It was small, light, and would last days on a charge. Wife ran hers through the wash 3 times and it still worked!

  12. As a user (still) primarily of flip phones, there are privacy conscious reasons to using any cellular network. 3G in the US has been labeled for discontinuation, but T-Mobile still supports 2G until next year.

    After that date, for anyone looking to a close enough experience, purchasing a KaiOS flip from your local electronic store (even convenience stores should have them) will include 4G, but you can disable the data service on them.

    A sad but convenient to some initiative is GPS moduals being required on 4G+ devices, but on these devices its typically Assisted GPS, which requires data to work. There’s all sorts of magic you can do with them.

    Freedomfi also can assist someone looming to implement their own cell network. I’ve created a few using lorawan and private LTE bands, just because. Eventually I’ll get my HAD article!

  13. My phone still worked when I tried it a few weeks ago. I don’t know how many g’s it has. But it has come to my attention that I need to buy a new phone in the near future because it’s battery capacity has deteriorated significantly over the last 8 or so years.
    alternatively, I could hack in three or four 18650’s That would get it a bunch of years of extra live, and a battery boost from those ridiculously thin newfangled phones.

  14. So *all* I need to do is make OpenBTS run on a Pi (or some other equally small processor), low power enough so it only extends 10 feet, and then cobble something together to transfer the 2g call I’m now receiving from my 20 year old phone into a wifi call ?

  15. It’s not 2G (or any G) but anyone can setup a VoIP Soft PABX and connect it to some VoIP phones and/or VoIP Analog Telephone Adapters (VoIP ATAs), and the Public Switched Telephone Network (PSTN).[1][2] Software for a VoIP PABX is generally free and open-source, Asterisk comes to mind, 3CX is another.[3][4][5][6] A Raspberry Pi will host a soft PABX just fine (if you can find one). Asterisk is free and open source. 3CX is (arguably) proprietary but like most Soft PABXs it has a forever-free tier and you can Bring-Your-Own-Hardware (BYOH). You will probably want to subscibe to a commercial VoIP Gatway service for things like connections to/from the Public Switched Telephone Network, 911 Emergency calls, Fax, Voice Mail, and lots of other things. I use a U.S. based VoIP Gateway provider named CallCentric [7], but there are many-many others to choose from and they are all either dirt-cheap or have a free tier. Finally, of-course for VoIP you need an Internet connection, nothing speedy though.

    * References:

    NOTE: All links below are examples only, not recommendations, and have NO AFFILIATION of any kind.

    1. Grandstream DP720 Dect Cordless VoIP Telephone $41.98


    2. Grandstream GS-HT802 2 Port Analog Telephone Adapter VoIP Phone & Device $40.00.


    3. Asterisk (PBX)


    4. Asterisk – Home


    5. 3CX Phone System


    6. 3CX – Home


    7. CALLCentric


    1. Yes there is, and for 3G4G too. It requires the equivalent of a local femtocell to be radiating while the local 2G or 3G service is being provided. So there may be regulatory issues.
      Also, authentication of the SIM might be a thing, unless you run the local network unencrypted.
      I did hear of a commercial product bridging to 3G and they might also be doing a 2G one.

  16. As someone who oversaw the upgrade of a fleet on thousands of widely dispersed 3G connections for machines, the biggest challenge is trying to convince the boss to upgrade before it gets switched off. Modifying the machines was easy in comparison.

    By the time he agreed our posts supplier couldn’t keep up with demand for new modules.

  17. Here in Austria only 2G/3G internet access will be switched off within a couple of months. I expect that voice/data calls and SMS will be available for another decade, because these services are used by most alarm systems and vendors have long-term contracts with mobile providers. Maybe 2G/3G will be dropped entirely from regular (cheap) mobile subscriptions in the future and the allocated bandwidth will be reduced, but providers would be stupid to kick out customers who pay the business (pricey) monthly fee and generate not much traffic.

    1. Here in nl onlu tmobile still offers 3g. Last month i finally replaced our 11 year old note2’s with pixels, bacause all our neighbours no longer 3g making traveling painfull. And soon here too. It sadnes me as the phones are actyally still quite reasobly useable.

  18. The issue for designers are largely around IoT devices with low cost, and long life unattended operation. Which low throughput technology can be implemented into the new device that has a good chance to be supported by a public network in 10 years? Once LTE-M was introduced in 700 MHz (mostly… some 800), that decision was initially easy. Depends where in the technology life cycle you are making this decision for your new device. Meters and other IoT devices can be in basements, and places where 3500 MHz 5G will not reach. Or in rural areas where 600/700/800 are it. Cellular operators trend towards upgrading their hardware over a 5 year cycle (that is the trend). Technical segregation makes leaving old technology be until it is in the way and must be removed. For example, some Canadian carriers operate 3 distinct technology lanes: HSPA+, LTE (and LTE-M), 5G (NSA and SA) segregated over three BBU platforms. Fortunately, IoT SIM cards can be carrier agnostic, meaning they can be purchased to operate on any available wireless carrier. Having worked for a large carrier, even internally, no one can be very clear about the future beyond 3 years. Sooner or later, the clock will run out on a technology and your IoT modem will need to be replaced.

  19. Who still uses 2G and 3G phones? People with 2G and 3G phones that are durable, still work, and who don’t need 4G functionality. And most importantly, the poor who can’t afford overpriced 4G and 5G phones.

    Demanding forced purchase of 4G phones when the cheapest still run into hundreds of dollars is a display of classism and privilege. You’re telling the poor, “you don’t deserve to have a phone”.

  20. Here in Europe all vehicles sold since April 2018 are required to have an eCall system installed. eCall needs a circuit switched voice connection. eCall2 does support 4G and 5G and does work on Voip/VoLTE.

    But if you have a car built between 2018 and 2021 it will be 2G/3G eCall and there is no upgrade path (other than trade in for a new car!) Herein the UK the ‘sunset’ date for 2G has been extended to 2030 – but don’t expect good service on a 2G mobile phone!

    Turning off 2G & 3G was a good decision for the network managers, but bad for their customers!

  21. Up until December of 2022, I was still using a Motorola V60S flip phone and I miss it terribly. The green lcd screen, primitive ring tones, touch texting, and great audio on phone calls made it my absolute all time favourite phone. Verizon shut down the network and I held on to the bitter end. I had found a battery for a Motorola radio that is still in production which fit the phone so batteries were never an issue. I even rebuilt the phone by putting the pc board in new shells. I absolutely loved that little phone. I absolutely hate using a smartphone. Texting sucks, battery life sucks, and it’s just an overall pita. I used to go a full 5 days on a single charge. Now it’s a day to ever other day between charges. I feel like I went backwards in technology.

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