GSM Module Does More Than Advertised

For many projects, a WiFi connection is overkill, too complicated, or too far away to work properly. Even though it’s relatively ubiquitous, sometimes the best choice for getting data to or from the real world is a connection to the cellular network, which can be done with the M590 module for about a dollar each. For that price, lots of people have had the opportunity to explore the module itself, and [marcrbarker] shows some of the extra, unadvertised, features it has.

Acting as a GSM module that can send and receive SMS messages is just the tip of the iceberg for this tiny device which we saw once before for a DIY GPS tracker. With a USB TTL serial data module, a lot more is on the table including answering voice calls and responding with DTMF tones, operate as a dial-up modem, connect with TCP, and even has some FTP capabilities. [marcrbarker] also suggests that it could do “call pranking” where it can send signals without being charged for a call.

There are a lot of details on the project site about all of this newfound functionality, and it reminds us of a time when it was discovered that not only was the ESP8266 a cheap WiFi module, but it could also run custom programs on its own. While the M590 probably can’t do all of that, it does seem to have a lot more locked away than most of us had thought before.

13 thoughts on “GSM Module Does More Than Advertised

  1. The Neoway M590 is a GPRS module. Hasn’t GPRS/UTMS capability been deprecated in the US in favor of LTE? Maybe idk what I’m talking about but what carrier would these work with in the US?

    1. GSM is definitely going out, and some operators are also phasing out 3G in favor of 4G/5G.

      It’s a bit weird, because those operators that are dropping 3G are leaving 2G in place for basic service and legacy support, while those that are dropping 2G are leaving 3G for legacy support…

  2. Depending on where you are you might seem 3G being retired before 2G.
    In the european country i call my home, there are so many machine-to-machine (m2m) contracts in place, that switching off 2G would be a disaster. And 3G spectrum is refarmed for 4G/5G. There will probably always be 2G coverage for the next 10 or so years, but the spectrum available will give you almost no data rate, but maybe enough for IOT.

    Apparently 4G modules are still far more expensive today, let’s hope some makes the espressif move and suddenly they cost 5$ or so and come with a nice SDK ;)
    Maybe Lora/Sigfox are alternatives?

    1. NB-IoT and LTE Cat M radios are coming up.

      Both of them operate under the point that you have unused guard bands between cell towers which can be used for narrow band radio, so they’re using a sort of reduced version of the regular in-band communications with long keep-alive windows to allow the devices to sleep most of the time.

      On the service side, you have a more or less regular phone contract – may be with a cell number but most likely not – and the interface behaves as if you had a cellphone with a limited internet connection. You get a gateway out of the carrier’s network and the preferred method is to use MQTT to send and receive messages.

      So it’s more flexible than sigfox and lora, you don’t need to sign up with some “thing network” third party platform to make effective use of it. The only issue is that carriers/operators are guarding the services very jealously and often refuse to sell you the sim cards – they want to provide the whole IoT solution as a service, using their devices and cloud platforms, creating the same issue as with lora and sigfox.

    2. NB-IoT and LTE Cat M1 are coming to replace those. Lora is fine for a bit of hacking and local solutions within a few miles radius, but it suffers from no control of the spectrum (inevitable congestion/interference) in urban areas and it’s dependent on joining some third party platform to get wide area coverage.

      Sigfox has similar problems – you have only one provider, and you have to connect through them. The only advantage is very wide area coverage where you have it – otherwise it’s a pain to work with. For example, every device you own belongs to some group of devices, which all share the same callback. They can’t act as individuals, unless you manage each device as an individual group.

      The cellular IoT solutions on the other hand can be bought in singles, work everywhere the carriers decided to do a software update on the tower, and they open you a pipe to the internet via the carrier’s gateway – then it behaves like a cellphone with a limited internet connection. Do anything you like with it.

      1. NBiOT and CatM1 are way too power hungry compared to LoRaWAN or SigFox. and more expensive too. cat M1 might be a way to replace the old GSM based automations (alarm systems, remote controlled gates, idk) which have continuous power feed (not battery operated). also you can’t neglect the fact that there is no worldwide IoT system based on 3GPP tech. if the same mexican-standoff-style roaming agreements remain in place, this crap will never go anywhere. current telcos are looking to climb back to the golden era of GSM by ‘monetising IoT’, whereas LoRaWAN provides you regional (eu, apac, americas) service with OTT providers at a really low barrier of entry. and the ‘new 3GPP sh1t’ called campus network, which is more or less a private 3GPP compatible hosted mobile infrastructure – you have this at a 2-3 orders lower price with LoRaWAN – and in almost all cases you will not require true worldwide mobility for these new IoT applications.

      1. That’s a back-formation for anglophones. It’s “Groupe Speciale Mobile” after the working group that developed it. I’ll let you translate that yourself.

        There’s nothing particularly global about it. The range, I’m told, is about 20 miles. And plenty of countries didn’t implement it. So it’s not really a good back-formation.

  3. I remember a GSM phone could become a GSM base station…
    Something called like osmocom-bb.

    Also VGA adapters can sniff GSM traffic.

    Also cheap GPS modules can be used as precise reference clocks.

    Also someone was controlling his RC car using 62th (?) harmonics of a radio device. What was that device I don’t remember.

    Lot’s of others in this interesting world.

    1. I think the VGA adaptors only transmitted. They were basically just 3x broadband DACs with USB 3 on one end and a VGA plug on the other. The guy handled the incoming signal with an SDR.

      That Osmocom-BB sounds interesting though. People discovered a lot of hacks in the early days, lots of early phones had engineering features still active. I think with the thinking that nobody would ever open them up to connect wires. The cost of the things was frightening, I’d have been scared to even risk answering one in case I broke it.

      I was on an early cellphone website the other day, Osmocom is a name I remember seeing there. Another early cellphone memory was the 1G phones. You could sniff the “pairs” just from hanging round a rail station or anywhere mobile phones might be. Once you had the ESN / MIN pair, you could imitate that phone. There was a “magic phone” that would soak up pairs in public til it had 10. Then it would use those 10 for making calls, til they were used up and you’d have to go sniff more.

      I dunno how the network handled caller ID but you’d think being called from random mobile numbers all the time would be annoying. Then again that’s if you HAD caller ID, most landlines didn’t, and most phones were landlines.

      There was a documentary on somebody who had a setup of hacked 1G phones, all calling premium-rate numbers in the Bahamas or somewhere with access to the international cash-splitting telco scheme, and easily bribed officials. 10 or so phones mounted on the guy’s wall, constantly ringing up 10 strangers’ bills, siphoning to the premium-rate company. I suppose the guy would take a hacked phone out in public now and then to collect more pairs.

      Then there was the thing where unscrupulous British journalists, the only kind we have, used a scanner and picked up Prince Charles talking dirty to Camilla in a hilariously inept way.

      Interesting times. But being able to pick up a wristwatch phone for pocket money now is probably better.

  4. 2G or not 2G.

    2G was dropped years ago in Australia.

    Now, for truly remote IoT you need to add a decent battery, charge controller, solar panel and expensive module and M2M plan to the BOM.

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