The Experience

To explain my newfound woes with this technology I must first tell a story for context. Last week at the time of posting my internet service went out, and after much debugging it seemed to be some physical problem of sorts somewhere between my house's service box and the ISP (as they claimed there was no outage on their side). To make matters worse, the ISP also said it'd take 5 days to send a technician (a bit absurd if you ask me but at least understandable as I'm sure they have a lot of other problems to deal with), so I was stuck with essentially nothing. For some this might not be a problem, but given I live a fairly connected life and work entirely remotely internet is something of a necessity for me to communicate with people and work effectively.

Upon thinking of alternative options I remembered I had bought a GL.iNet GL-XE300, a type of router/4G modem, and a SIM card from US Mobile (who I heard to be fairly cheap for my style of sparse usage, backed by T-Mobile) for similar cases when traveling without any access to internet. Most people would of course use a smartphone in this case, but I do not own one for various reasons. As mentioned previously to me there is nothing wrong with the concept of a wide-scale wireless network, and it would be foolish to not utilize it when I had the tools to do so in a way I was happy with (via a desktop computer rather than a smartphone). I then went about setting the device up for the first time which turned out to be quite simple, only taking a few minutes to get everything up and running. To my surprise as well it connected to the mobile network just fine and I was able to access the internet through it, success! Of course, I was right to be shocked by how painless the whole process was, the pain was yet to come.

A short time after starting to use the network the connection dropped out, rather I was still connected to the 4G network, but the packets were being dropped. At first I thought it was just yet another outage of sorts on the mobile network's side and ignored it, though upon coming back later and having the same issue I began to think it was something on my side of things. I messed with configurations for a while and tried different computers, eventually finding that web traffic was being redirected to a static page which informed me I was out of data. How could that be I wondered, I only used around 50 MiB or so and I had over a gigabyte attached to the SIM card in question.

With little other option I contacted the provider's support, hoping perhaps they could sort things out for me. Those with more experience with smartphones and mobile networking already likely have pieced together the situation and know what's going to happen next, but I did not so I went through their questions. Eventually I was asked something akin to "Is this a modem?" and I immediately knew what was going on. Indeed I was informed that they do not support such devices on their network and that was the end of any support I was going to get from them.

Knowing now the game they were playing I did some more research and learned, many mobile networks use various packet inspection methods that'd surely put China's Great Firewall to shame to identify different sorts of devices behind the connection itself. TTL-based connection identification for example seems to be one of the most common ways to determine if tethering is being used through a mobile device versus its typical "data" usage, as the tethering case would have a TTL value 1 less than what is typically expected (or something wildly different). My mistake was not realizing all this was in place in advance, and no doubt my connection sent all manner of unusual traffic, leading to what I assume is some sort of data-based ban on that SIM upon the system realizing what I was doing (perhaps someone who knows this stuff better could confirm that is typical practice, but it does appear to be the case to me that I was blocked somehow).

This of course is the crux of my frustration. I don't think I even have to say how utterly moronic all of this is, but I will anyways.

Reasoning

Firstly, it is absolutely delusional that companies classify tethering and data as different things, maybe I am just an old boomer completely out of the loop in mobile land (because well, I am), but as it stands from a modern perspective this makes no sense. I am sure there's some sort of historical background as to why these features are separate and evolved independently, but I do not care. One could also point out that the concept of a "call" or "text" is also under the more modern general umbrella of "data", and I'd agree with you. There is no reason to classify such things distinctly rather than just measuring them as data usage (which is fundamentally the thing you're paying for on a mobile network), but at least in that case most companies offer plans with unlimited calls/texts due to how little bandwidth they actually consume, making it somewhat irrelevant. As an aside, this criticism applies to traditional ISPs too, gone are the days of circuit-switched phone networking and since it is all VoIP now you should not need to pay a separate fee to do what you can do for free via dozens of programs over the internet you're already paying for.

Secondly, and perhaps even more remarkably baffling, is the arbitrary distinction between something like a smartphone and a 4G modem. To say your mobile network company "does not support modems" is so painfully stupid given smartphones themselves (and other supported devices) have 4G modems within them, just as an integrated component rather than a separate device. These companies seem to be trying to twist the word "modem" into some distinct class of evil devices used by hackermans, presumably to screw people over as effectively as possible and trick everyone else into supporting them. That to me at least is one of the only logical explanations for this level of deception, people with USB 4G modems and similar devices will be using them mostly with computers after all, and this typically means they will be invoking more data-heavy workloads which stress the mobile network more than a smartphone would. Naturally people actually using the services they are paying money for is a terrifying concept to companies who likely oversubscribe their cell towers to death, so finding some way to curb this type of network usage seems like a likely conclusion. Another possibility is that this is some higher level business agreement with smartphone companies, making it so more people will be forced to buy their devices to interface with these admittedly useful wireless networks, a tactic which is not new at all (see: the "you need to own a smartphone" line of thinking companies have everyone wrapped up in by intentionally making everything depend on owning one, but that's just a topic for another day).

All things considered, one might say that it's simply the company's choice to restrict what types of network usage they permit as they are after all leveraging this fact most likely to reduce prices for everyone overall (a common tactic even for traditional ISPs), and that the solution here is to just find a company which does provide the data connectivity I desire (likely at a premium). This is of course true, I am not here to say what a company can or cannot do legally, but I do feel that there are deceptive business practices going on here which should be discouraged:

Firstly, companies should not advertise bandwidth or network data caps without giving the exact details to how any limitations function. This applies to traditional ISPs too of course, oversubscription is a nasty "technically correct" tactic by saying you are paying for "up to" some amount of bandwidth without actually providing the details of the shared connection you're on. To make matters worse, most people do not interpret it that way and expect to actually get the number they see on their service plan as the "up to" portion is usually hidden somewhere in tiny text or under an asterisk to trick people in the maximum legally permitted manner. Similarly, saying you are paying for 1 GiB of mobile data and either cutting someone off or throttling them to oblivion before they can reasonably even use that amount of data is equally deceptive when this information is not displayed up front. Consumers need to understand the quality of the service they are purchasing beyond just a single number when this level of bandwidth sharing and cost-saving complexity is involved, as without this making informed decisions to drive competition becomes much more difficult. This tactic is of course used in every industry beyond just the narrow scope of mobile networking I am focusing on here, forcing consumers to turn to independent reviewers or other more honest knowledge sources if they wish to actually make an informed decision. A company should strive to be honest and fairly present itself, and as such relying on these tactics to exploit consumer ignorance is not only harmful to competitive capitalism itself, but is also fairly immoral and should be generally discouraged by everyone (as we're all the consumers being exploited here).

Secondly and perhaps most relevant is the case when a company tries to police the usage of products or services you purchase from them, this is absolutely inexcusable behavior. This is of course also done in various other industries, however in my case this can be observed in how the company says I cannot use a service I paid for via a dedicated 4G modem when it is functionally identical to the type found in smartphones. The company should have no say in what I can and cannot send packets from, in the end it's all just packets which they can process no different than any other (again, functionally identical). Of course if these packets were somehow different in a way which was disruptive to their service (for example some sort of DoS attack or otherwise illegal), then there'd be some cause for legitimate concern, but there is nothing illegal about using literally any other device other than a smartphone behind a 4G connection. One may rightly point out that the service I paid for indeed did say 50 paragraphs down in a contract no one reads that they do not permit such devices on their network and it's my fault for not reading it, but I do not care. They may even have some profit-centric reason for it as mentioned previously, but I still don't care. The point is that they are trying to tell me what I can and cannot do with something they should have no jurisdiction over merely because they can, and to me that is evil.

Just for reference I figured I'd put the actual terms relevant to this discussion the company provided here, though also because found the placement rather amusing. As part of their "acceptable use" policy they say not to use the network to spam, distribute malware, launch denial of service attacks, or look at child porn, all understandable generally illegal activities. Intermixed in all of that however is the following:

When you buy and use our Services or any Devices you agree that you will not misuse or abuse our Services or Devices by doing, among other things, any of the following:

1. modifying your Device from its manufacturer's specifications;
2. activating a Device on a Service Plan or with a feature or product not designated for its use;
3. inserting a US Mobile SIM card into a modem, router, laptop, or other signal broadcasting device.

Your Device uses a US Mobile SIM Card to access our Data Services. You are prohibited from using a US Mobile SIM Card with any device other than a basic phone, smartphone, or tablet device to access our Data Services.

The language used here is so insanely controlling over their customers, it's amazing anyone could've written this and actually thought it was a good idea. I surely hope no one unironically thinks that daring to use anything other than a smartphone to connect to their network is on the same level as committing denial of service attacks, and that this is all some elaborate ruse to cut down on bandwidth as mentioned previously, but who can say.

Closing Thoughts

With all that in mind, hopefully I will be able to find a better provider that doesn't have such foolish limitations on what can be used on their network, and at least now I know to be much more careful when using a computer over a mobile network, so if anything I thank the company for this excellent learning experience. For everyone else's sake, remember to ensure the TTL out of the modem set to an expected value (typically 64, but may need to be 65 to be decremented once by the modem itself depending on where it's being set) and ideally use a VPN to prevent any deep packet inspection of the actual traffic (to maks various unencrypted indicators that can identify computer vs smartphone usage). I am not an expert in this sort of thing though (clearly), so do your own research for your own specific device and network.

After an experience like this, I think some may understand why I detest the smartphone industry as a whole and tend to avoid it. This is merely one portion of a larger problem which I hope in time people will recognize, but I've already ranted enough for today. All I wanted to do was to use a mobile network to help myself in a time of need for a few days, but that was apparently too much to ask because I wasn't connecting with a $1000 iPhone, so they took my money (by not letting me actually use what I paid for) and screwed me over. I hope some executive responsible for this sort of policy is making an extra 5 cents off of my momentary ignorance and lack of one-off network usage, though something tells me the cost of me leaving their service will make that hardly worth it.