Database Info

Phone carriers put the squeeze on

Apparently they got hip to the tethering several apps were removed from Android market. One they really didn't like was Pdanet it is no longer on market. Does it really work that well? You can still get on the freeware site. They are too late, once it's out there its out there. Hard to put the genie back in the bottle.

Yeah, I am not sure why they are getting anal about this stuff. How can they tell the difference where the data originates?
Plus, they can't do anything to people using the Verizon 4G LTE spectrum. The FCC clearly laid out, when they sold the spectrum, that they couldn't limit what people do with their handsets, even with data usage. So they can whine and complain all they want, FCC supersedes VZW TOS.
Apparently 3G is still fair game for them to limit, but I don't care. I don't think they should have the right to tell me what I do with the data that I pay for to be sent to and from my handset, no matter what their TOS says. Data is data, bits are bits, no matter where they go and what they are used for.

About the only company offering true unlimited data thus far is Sprint, but I did read that they will eventually be adding a tiered plan for tablets.
It won't surprise me if in the near future that each provider follows suit like Apple & offers their own Market, in fact I'm surprised they haven't capitalized on it already.

You're buying data service for the handset. When carriers sell wifi hotspots plus service, it is in their financial interest to make sure that unauthorized hotspots are shut down.
There isn't anything illegal about them disallowing unauthorized hotspots.
The free ride ended for jailbroken iPhones, this was just the next logical step. Since Google/Android needs to have carrier buy in, if the carriers ask to shut down apps that violate the TOS, you can bet they'll be shut down.
Even if you side load an app, since all the apps just do NAT it's a trivial packet header inspection to detect use. That's what AT&T is doing - they notify people when they detect tethering/hotspot use.
Bottom line - if you use it, you'll need to buy the add on.

I have heard that you can put your handset in airplane mode, turn on wifi, then load up the market and still download any tethering app you want, pdanet included.
[EDIT] I am att and just tried this with my inspire. On 3g the pdanet app would not show up, so I turned on airplane mode and wifi and connected to market and voila, pdanet did show back up!
So this method is confirmed as a working solution to the carrier blocked tethering apps dilemma. ;-)
Let me know if that works out for ya.
Sent from my GTablet

hitekredneck said:
I am att and just tried this with my inspire. On 3g the pdanet app would not show up, so I turned on airplane mode and wifi and connected to market and voila, pdanet did show back up!
Click to expand...
Click to collapse
Wait so then that means pdanet was not pulled from the Market, particular carriers just block it then? Interesting...

EL TEJANO said:
Wait so then that means pdanet was not pulled from the Market, particular carriers just block it then? Interesting...
Click to expand...
Click to collapse
Yes, this has been known for quite some time. There is a config line, I think it is in the build.prop file, that identifies your device when connecting to the market. This line makes it possible for the goog market to make certain apps available or not available via carrier request. There are ways of getting around this though which can be found with the search feature here. There are also a few apps that will fake your devices id on the android market so you can get around the blocking of certain apps.
Sent from my CM7 OC'd G-Tablet

Fully utilizing internet connecting mode for bittorrent

[Win7]
When using the internet connection mode does the phone have a built in firewall or port blocker? My laptop was already connected to the internet through my home's WiFI internet and I was downloading off bittorrent using µTorrent. I was getting decent download speeds on my torrents, but almost nothing on upload. Knowing that the LTE network is more balanced and generally faster than my home network I connected my phone to my laptop via usb and selected internet connection mode.
At this time I noticed no difference and opened task manager to check network utilization. Task manager showed that my home network connection was being used and LTE was not being utilized at all. So I disconnected from my home network and waited for µTorrent to adjust to my phone's connection. After tinkering with some settings in µTorrent it showed the "!" at the bottom right notifying me that either the port I've selected is blocked or some other setting is stopping my connection from being used to it's full potential. I again check task manager and as far as network utilization goes it was around ~1% and my download speeds are far from what they should be, and far worse than when I was just on WiFi.
So I connect back to the WiFi and µTorrent starts behaving how it did before I tried to use my phone. Task manager shows more activity on the WiFi connection and still around 1% for the phone's connection.
My concern is how can I maximize LTE's potential when for bittorrent. Is there some kind of built in port blocker or firewall element? Or is it some kind of protection set up by Verizon and they know I'm using their network for bittorrent? I was getting consistent 5MBps Down and Up when I tested my laptop using internet connection mode, so network stability shouldn't be the issue. Any thoughts?

I haven't tested it, but I'd be willing to bet that the built-in internet sharing mode on the phone blocks certain ports. You could try using a tethering app like EasyTether or PDAnet.
Are you rooted? You could try Wireless Tether for Root Users, and see if you get any different results with that, too. I had some issues using VPN from my OG Droid because there were some blocked ports when using USB tethering, but once I rooted and started using Wireless Tether, all my problems went away. It'd be worth checking out. If you're not rooted, I would imagine that the wifi hotspot would act the same way (although it's only free for another week or so).

Sweet! Another person who's going to get us capped.

Ya, runniNg bittorents off your phone is RETARDED
Sent from my 4G LTE Thunderbolt using XDA Premium

EEdaesung said:
[Win7]
When using the internet connection mode does the phone have a built in firewall or port blocker? My laptop was already connected to the internet through my home's WiFI internet and I was downloading off bittorrent using µTorrent. I was getting decent download speeds on my torrents, but almost nothing on upload. Knowing that the LTE network is more balanced and generally faster than my home network I connected my phone to my laptop via usb and selected internet connection mode.
At this time I noticed no difference and opened task manager to check network utilization. Task manager showed that my home network connection was being used and LTE was not being utilized at all. So I disconnected from my home network and waited for µTorrent to adjust to my phone's connection. After tinkering with some settings in µTorrent it showed the "!" at the bottom right notifying me that either the port I've selected is blocked or some other setting is stopping my connection from being used to it's full potential. I again check task manager and as far as network utilization goes it was around ~1% and my download speeds are far from what they should be, and far worse than when I was just on WiFi.
So I connect back to the WiFi and µTorrent starts behaving how it did before I tried to use my phone. Task manager shows more activity on the WiFi connection and still around 1% for the phone's connection.
My concern is how can I maximize LTE's potential when for bittorrent. Is there some kind of built in port blocker or firewall element? Or is it some kind of protection set up by Verizon and they know I'm using their network for bittorrent? I was getting consistent 5MBps Down and Up when I tested my laptop using internet connection mode, so network stability shouldn't be the issue. Any thoughts?
Click to expand...
Click to collapse
I'm sure they block ports, and to be honest, I sincerely hope they block torrenting on a cell phone. Why not use your wifi?

As others have already stated use your home internet connection as I like having unlimited data.
Sent from my ADR6400L using XDA App

eallan said:
I'm sure they block ports, and to be honest, I sincerely hope they block torrenting on a cell phone. Why not use your wifi?
Click to expand...
Click to collapse
It's because LTE's upload speeds are superior to my home connection. And for people worried about getting capped, there is no way I could get within the 10% of users who are throttled.
^_^_^

It's people like you that are going to ruin it for the legitimate rest of us. There is absolutely zero reason you should be torrenting on your phone, thats what your home connection is for. As mentioned earlier I hope that they do block the ports as I love my unlimited data plan knowing that I don't have to check my usage every 3 minutes like I would with att and their 2gb limit.
So in short, stop doing what your doing and ruining it for the rest of the U.S.

EEdaesung said:
It's because LTE's upload speeds are superior to my home connection. And for people worried about getting capped, there is no way I could get within the 10% of users who are throttled.
^_^_^
Click to expand...
Click to collapse
Neither matters soon Verizon will take away the unlimited tethering plan and you will be sol. Even if you use a rooted wireless hotspot Verizon will know when you start racking up the gbs.
Sent from my ADR6400L using XDA App

I didn't realize it was such a big deal. Especially since it's a service I pay for, and I wasn't planning on torrenting the entire internet.
Since there are so many concerns of losing unlimited data, I'll think twice before using my phone's network to do any heavy downloading or uploading.
^_^_^

EEdaesung said:
I didn't realize it was such a big deal. Especially since it's a service I pay for, and I wasn't planning on torrenting the entire internet.
Since there are so many concerns of losing unlimited data, I'll think twice before using my phone's network to do any heavy downloading or uploading.
^_^_^
Click to expand...
Click to collapse
First off you are not paying for the Mobile Hotspot service it is free until May 15th.
Second as of right now there is no real threat of losing the unlimited plan. Verizon has not said anything about taking it away and as of right now you could up and download 100gb of data and Verizon may say nothing. The problem is that we just don't know. We could wake up tomorrow and all have capped plans (As it is in the contract we all signed when we bought our phones Verizon can change the details of the data plans basically at any time they want) Yes there is like a 1% chance of this happening at the PR Verizon would get from this would most likely run them into the ground but the thought is still out there. And for most of us who only use ~5gb of data per month or less just don't want to worry about that odd month when maybe some new series comes out and they use 50gb.
TLDR: As of right now its more of just a fear of losing it than anything else and not really something to be too worried about ATM.

EEdaesung said:
I didn't realize it was such a big deal. Especially since it's a service I pay for, and I wasn't planning on torrenting the entire internet.
Since there are so many concerns of losing unlimited data, I'll think twice before using my phone's network to do any heavy downloading or uploading.
Click to expand...
Click to collapse
Or at least posting here about doing so.

EEdaesung said:
It's because LTE's upload speeds are superior to my home connection. And for people worried about getting capped, there is no way I could get within the 10% of users who are throttled.
^_^_^
Click to expand...
Click to collapse
There is a difference in using a phone to web browse, or to watch a movie or whatever, and maxing it out 24/7 and saturating the connection to torrent.
One is a bad idea IMO.

Got it guys. I agree with all previous posts. I don't want to get capped either and I won't be a factor towards it.
^_^_^

That's bull...you pay for it you use it how you want...I dare Verizon to come at me already and I told them I'm rooted...I ruin my OG Droid and they still replaced it...they make hundreds of millions of dollars and I pay an already high phone bill...too bad there is already an Frostwire app

currensy said:
That's bull...you pay for it you use it how you want...I dare Verizon to come at me already and I told them I'm rooted...I ruin my OG Droid and they still replaced it...they make hundreds of millions of dollars and I pay an already high phone bill...too bad there is already an Frostwire app
Click to expand...
Click to collapse
LOL. Another reprobate weighs in.
"you pay for it you use it how you want"
So, exactly how much are you "paying" for tethering (not that which is currently offered as a freebie, but the theft of services your comment implies)? Your comment might be better phrased "you pay for it, I use it," since it's going to be paid for by someone, and if not by those who rationalize stealing it, then by the rest of us.
"they make hundreds of millions of dollars"
I'm guessing (assuming you're not still in Jr. High, as your attitude suggests), that you make thousands of dollars. So, I'd be justified in stealing from you, by your logic.
"I pay an already high phone bill"
If it's too high, it's very easy to cancel the service. Obviously, since you're posting in the TB forum, you have one, which means you've recently renewed your service. Which is it - you agreed that the value per dollar was acceptable, or you're just stupid?

You have to disable other connections after enabling internet sharing mode. Windows doesnt magically switch to a better connection on its own.
People should also remember that torrent does not mean illegal. He never mentioned what he was downloading. Apparently no one else in this thread has ever downloaded a linux distro, since bittorent is a primary way to do it. Certain games and game content are distributed legally through bittorent as well along with other software (generally opensource stuff).
The other day I didn't want to wait 30 minutes for aptitude to update my system on my 630KB/s average DSL, so I plugged in my phone to internet sharing on LTE and it was done in < 5minutes @ 2500KB/s average.
Verizon's network does not block ports as far as I know, but you are behind NAT, so you aren't going to be running any sort of server either on the public internet or easily connecting to your phone from a remote location.

Why do people take threads like this off the rails so quickly? The OP asked a simple question that didn't really warrant a philosophical decision. Imposing your will on the miniscule number of TB users who visit XDA won't make any appreciable impact on Verizon's attitude towards sanctioned network use.
OP, please report back if following "yareally"'s suggestion of disabling other connections works once ICS is enabled. Also, are you able to bridge your connection to the TB's in Windows? It'd be sweet to be able to merge WiFi (for speed) with LTE (for reliability).

currensy said:
That's bull...you pay for it you use it how you want...I dare Verizon to come at me already and I told them I'm rooted...I ruin my OG Droid and they still replaced it...they make hundreds of millions of dollars and I pay an already high phone bill...too bad there is already an Frostwire app
Click to expand...
Click to collapse
If you use frostwire... you probably still have a myspace...
Lol at your made-up story, VZW is here on XDA also... they just might come at you bro...
In regards to the OP, lol at anyone who thinks this one single guy is going to be the downfall of unlimited data...

Nooter said:
OP, please report back if following "yareally"'s suggestion of disabling other connections works once ICS is enabled. Also, are you able to bridge your connection to the TB's in Windows? It'd be sweet to be able to merge WiFi (for speed) with LTE (for reliability).
Click to expand...
Click to collapse
Nope, cant bridge them in windows and use both (that is, it's not as simple as selecting both connections and clicking bridge). There's some ways to distribute their use over *nix and/or using a router and using them as separate connections, but it's not worth the time/effort. If you're really interested in doing it, there's some discussions about it on the xda forums already and elsewhere if you google around.

Tethering on WP7 - pimp slapped by AT&T

Did the obligatory searches - didn't see anyone else in my shoes.
AT&T sent me a text and a letter in the mail telling me that they'd detected me tethering and that they would be changing my plan automatically to a tethering plan if I didn't stop.
I'm not sure how they figured it out, as I am pretty sure from past research on this forum that both tethering and cell data use the same APN. My only guess is that while on vacation, a massive data spike gave it away, as my phone was my only connection to the outside world.
This is fair warning to everyone that it seems AT&T is after tetherers.
Home from vacation, my data usage has gone way, way down so:
Was this a bluff by A&T based oin data usage?
Does anyone know the means which AT&T discerns who is/isn't tethering?
Has anyone else gotten this warning?

Well if you went over their cap it probably set of a few alarms.

It's possible to detect heuristically, if you're looking for it. If you're using deep packet inspection (which they probably aren't), it's dead easy (look for things like desktop browser user agents).

kenikh said:
Did the obligatory searches - didn't see anyone else in my shoes.
AT&T sent me a text and a letter in the mail telling me that they'd detected me tethering and that they would be changing my plan automatically to a tethering plan if I didn't stop.
I'm not sure how they figured it out, as I am pretty sure from past research on this forum that both tethering and cell data use the same APN. My only guess is that while on vacation, a massive data spike gave it away, as my phone was my only connection to the outside world.
This is fair warning to everyone that it seems AT&T is after tetherers.
Home from vacation, my data usage has gone way, way down so:
Was this a bluff by A&T based oin data usage?
Does anyone know the means which AT&T discerns who is/isn't tethering?
Has anyone else gotten this warning?
Click to expand...
Click to collapse
This is an issue that has been coming up in a lot of android/ios threads, and everyone has their own theory, but my guess is they're conducting individual (automated) audits when they detect subscribers with high usage. It would take a ridiculous amount of computing power to look at the IP packets & track every TTL hop of every subscriber with a data plan, but if your usage is over a certain amount, or in the arbitrary "top 5% of consumers", they're probably flagging your account for an audit of TTL hops.
That's the only way I can think of that would affect iOS, Android, Blackberry and WP7 all in the same way. Some people have been saying it's mostly iOS users, and others say its mainly Android or WP7 or whatever, but there's no evidence for any particular platform versus the others. I'm sure they're capable of figuring out each platform's standard TTL, so if they know what device you're using, they can easily identify any device you connect via your phone.
The only exception to this seems to be the Blackberry Playbook bridge feature, which is essentially just projecting the phone's browser session onto the Playbook's screen (albeit quite effectively). As far as I can tell, the only way they're identifying Playbook tethering is when people download the bridge app from App world as opposed to rroy's OTA method.

Were you tethering via internet sharing? I've received the same message from AT&T but only after turning on internet sharing for the first time. I tethered for over USB for 10 months before that with no problem. When I first got the message I stopped tethering completely because I didn't know what caused it (though it could of been the 13GB of data I was using). After discussing it on here I came to the conclusion that the message from AT&T was only received after tethering over Wifi, and that there were no issues with USB tethering. I've tethered since then and haven't heard anything from AT&T. So what method were you using? And if you say only USB it will prove my theory wrong.

Searching first is great, reading the sticky post would also be a good idea.
No Questions in the development section please.
Thread moved to WP7 Q&A

I received a text, an email, and a letter from AT&T. They just want more money from people to change to the 4 GB with tethering.
Sent from my SGH-i917 using XDA Windows Phone 7 App

jkern10 said:
I received a text, an email, and a letter from AT&T. They just want more money from people to change to the 4 GB with tethering.
Sent from my SGH-i917 using XDA Windows Phone 7 App
Click to expand...
Click to collapse
Same here...I have only tethered once since getting these warnings, I wonder if they would actually change my plan though.

wow I had gotten the htc titan but i switched to tmobile and the radar 4g just because tmo seems to turn a blind eye to tethering...

i just got an android tablet wi-fi only but i need to access important docs on the road, if i enable wi-fi tethering on my Samsung Focus and use it just once do i get a warning telling me to stop?

No. You have to be brazenly stupid like I was and eat gigs of data first.

thanks for the quick reply, so what i need it for it wouldn't send any red flags that i'm using wifi tethering

Just keep your data below the throttling threshold of your plan and they'll have no reason to do deeper inspection. You should be home free.

Its still stupid that they have special plans for tethering, I have unlimited data, but I'm not allowed to use it how I want. Bull****. Its criminal.
Sent from my Focus S (SGH-i937) using Board Express Pro

ATnT has definitely strayed away from customer satisfaction. I understand that the need to keep there Data Plan operating at peak efficiency requires them to throttle back certain users, but the way they go about doing it....for shame.

AT&T and Tethering

I know this is a frustrating subject for all AT&T users. Does anyone know what they are using to track tethering. I ask because I have been with AT&T over 10 years and have in the past tethered without a plan. However today I received notice that I am going to loose my unlimited data plan if I do not stop tethering, sad part is I am not tethering or have I been tethering at all in the last several months. I do stream A LOT so I know I am on their list, but honestly I generally go over 3GB so I am not a data hog. I spoke to AT&T's version of customer service and request that they tell me the exact technical specification of the test they are using to determine I am tethering, the answer was, "I don';t know, my system tells me that so it must be true". I then asked what app on my device is causing the issue, "I don't know". Finally I asked how can I stop a behavior my phone is doing if I do not know what if causing the problem? "I don't know". The one thing he (a "supervisor") did know was that I could fix everything by changing my plan and paying more. I am now waiting for his manager to call with an explanation, but it would be good if I actually had some facts to fight with. Most everything I know about AT&T and their policies is completely subjective and open to interpretation.

I've heard of this happening before, and I don't think they really "track" it at all. I think all AT&T is doing is going by your bandwidth. They assume if you're regularly pulling down that much data that you must be cheating somehow.
If you're regularly using 3GB a month, that's probably what's on their radar screen. Keep complaining and insisting that you've done nothing wrong, and they should back down. Ask for some proof, which I doubt they can provide.
I tether all the time, but keep my data usage down, and I've never gotten a warning.

SMH at your story. This is ridiculous! Keep fighting, man. Don't succumb to the beast! :sly:
Sent from my One X using xda app-developers app

Lol, I got a letter in the mail... Apparently they track... Now the question is .. disabling ARMS?
WCX HTC One "Hell of a fast phone" X

I got a warning to seems they can track it better now.
Sent from my One X using xda premium

Any of you guys using the Foxfi app from the Play store and the proxy addon? I've been using it on At&t with my Nexus 7 and haven't been notified.
Sent from my HTC One X using xda premium

Also, if the new share data plans work out for you, i believe tethering is included. I'm switching my wife and I over to that plan today (supposed first day they are turning it on). It'll save us about $25/month. But the plans aren't for everyone... Some it increases their price.
Sent from my HTC One X using xda premium

I've seen this discussed on other device forums here on XDA. No definitive answer was ever given on how AT&T determines whether you are tethering. One person who seemed to have a good degree of technical knowledge stated that every single data packet coming from a tethered computer are tagged differently than just phone use, and that any carrier can detect that tagging easily. Other people disputed that statement. I personally don't have the technical knowledge to say either way, but it seems feasible.
I personally doubt they go by bandwidth alone. I frequently go over 3 GB per month, sometimes close to the 5 GB throttle limit. Sometimes download close to 1 GB a stuff in a single day. But all on the phone (not tethered), and have never gotten the warning. Maybe they look for patterns, but not bandwidth alone.

redpoint73 said:
One person who seemed to have a good degree of technical knowledge stated that every single data packet coming from a tethered computer are tagged differently than just phone use, and that any carrier can detect that tagging easily. Other people disputed that statement. I personally don't have the technical knowledge to say either way, but it seems feasible.
I personally doubt they go by bandwidth alone. I frequently go over 3 GB per month, sometimes close to the 5 GB throttle limit. Sometimes download close to 1 GB a stuff in a single day. But all on the phone (not tethered), and have never gotten the warning. Maybe they look for patterns, but not bandwidth alone.
Click to expand...
Click to collapse
I've seen that theory as well. But being able to identify tethered packets is not the same thing as being able to monitor all of them all the time. It's the latter that I am not certain is feasible given the number of smartphones on AT&T's network.
One thing that is certain is that AT&T is not consistent in how they do this. I've seen people get nailed after a single tether; others--like me--have been blithely tethering for years without any trouble. I've also heard of people like the OP, who get tagged even though they aren't tethering at all.
I continue to think that bandwidth has to be the biggest part of it. I suspect they watch for heavy usage, then pay closer attention to those accounts.
Another thing: AT&T is known to give certain perks and leeway to larger accounts, such as letting you upgrade more frequently. I have a big family plan with three smartphones, unlimited texts, Family Map, etc. I've often wondered if I'm on some kind of "let them alone for now" list given how much I tether.
In any case, I'm switching to the new sharing plans (which launched today), which include tethering, so it will be moot for me at least.

iElvis said:
I've seen that theory as well. But being able to identify tethered packets is not the same thing as being able to monitor all of them all the time. It's the latter that I am not certain is feasible given the number of smartphones on AT&T's network.
One thing that is certain is that AT&T is not consistent in how they do this. I've seen people get nailed after a single tether; others--like me--have been blithely tethering for years without any trouble. I've also heard of people like the OP, who get tagged even though they aren't tethering at all.
I continue to think that bandwidth has to be the biggest part of it. I suspect they watch for heavy usage, then pay closer attention to those accounts.
Click to expand...
Click to collapse
Completely know what you mean when you talk about being able to identify the packets vs. actually monitoring all accounts. My feeling is that this is the main reason the enforcement is so inconsistent, that AT&T simply does not have the resources to monitor all the accounts this way. As you suggest maybe bandwidth is the first red flag, then they look at the tagging after that. And whatever the system is, it seems to be evolving ("improving" in the eyes of AT&T), as more people are getting caught.

Interesting feedback. I think I have figured it out. I was just guessing at my data consumption at 3GB, I actually pulled a report and looked. I average between 1 and 2 GB of data a month (pretty shocking to me, guess I use wifi more than I realize), last month it doubled to 4GB. It must be because I doubled my usage in one month, that must have set off a flag.
Still waiting for that manager to get me proof.
On a side note it felt really good to answer their survey texts with a 1 and not a 10.
I will update this thread if I get more information from the "manager". I am to stubborn to let AT&T win this one. Almost makes me want to start tethering again.

cyber_pete said:
I will update this thread if I get more information from the "manager". I am to stubborn to let AT&T win this one.
Click to expand...
Click to collapse
Good for you, man. Be interested to see how it turns out. Good luck.

I also just got a letter like this today. I've had unlimited data for four years, and I've tethered very sparingly over the years with the likes of PDANet, WiFi Tether, etc without being notified by AT&T. The only time I've really needed to tether was for the one week out of the year when I vacation to a cottage that doesn't have an internet connection. I went on vacation about a month ago, and tethered using the built in Hotspot with CleanRom's Hotspot Hack. I called AT&T after reading the letter over, and the rep told me that they did detect tethering activity on my end. I ended up telling her that I used a tethering app from the Play Store for the one week that I was without internet, but that I only used it in that instance and that I would prefer to keep my unlimited plan. She just asked that I delete the app from the phone, and cease tethering, and assured me that I could keep the plan by doing so. So, it seems as though their plan of attack is to enroll you in plan that enables the Hotspot functionality if they don't hear from you, but if you call and insist on keeping your unlimited plan, hopefully they will honor that like they did for me. Good luck!

Is it possible they are looking at the browser type? I've heard that browsers which don't normally run on mobile devices can get you caught.

smartphonesanonymous said:
Is it possible they are looking at the browser type? I've heard that browsers which don't normally run on mobile devices can get you caught.
Click to expand...
Click to collapse
That's the User-Agent factor, and yes they can get you that way, if you've gotten far enough onto their radar screen that they're reading your packets.
But no one really knows for sure how exactly they're doing it.
I, since I went to a shared data plan a few months ago, have come in from the cold.

Wow, zombie thread.
Sent from my One X using Tapatalk 2

USB tether with SSH and VPN
To carrier, it just looks like an ssh connection from your phone, everything else is encapsulated inside that doubly encrypted channel
(openvpn encrypts, so does ssh)
-- IP packet "signatures", Browser User-Agent, all invisible to carrier.
root not required, unlock/mod not required. works on stock unrooted device.
should work with any android phone, any carrier, any plan (that includes Internet access on phone)
(usage will still count against your data limit if you have a capped plan - mostly useful with unlimited plans)
carrier will still see your usage so they still might become suspicious, they just can't prove anything
use this advice at your own risk
it will use double the bandwidth on your HOME connection - everything has to go in, and
then right back out - may not be useful if your home internet is capped
.....
setup openvpn server on home PC connected with wired broadband
setup openssh server on home PC
setup proper passwords/keys for both to protect access.
use non-standard ports for greater security
(if you have a home router, be sure to forward the ports for both SSH and openvpn through it from "the outside" to the ssh/openvpn server)
if your home router is DD-WRT or similar, you may be able to do sshd and openvpn server right on the router, skip the PC.
.. EDIT: you will need to know the IP of your home connection to connect to it remotely. a dynamic DNS service can be useful for this ..
install sshdroid on phone.
install openvpn and adb on laptop
...
ok, you are out and about, and want to tether your laptop.
turn OFF wifi on phone.
enable usb debugging on phone.
connect laptop PC to USB on phone (connect type doesnt matter, charge-only is fine)
start sshdroid, have it ssh to your home PC and forward a tcp port for openvpn
use 'adb forward' command on laptop to forward the openvpn port from the laptop to the phone.
run openvpn on laptop, configure it to connect via localhost:xxx (where xxx is the port thats forwarded by adb to the phone, then by ssh to your home PC.)
use vpn tunnel for internet access
"whatismyipaddress.com" for laptop should show your HOME internet IP.
- this is just an overview, you will need to know how to setup the details of these apps and services, especially openvpn, in order to make this work. If you don't understand how to do so, find someone that does, or pay your carrier for the service.
- no wifi support, so no way to tether a tablet or anything else that can only connect via wifi; only a laptop or other PC that has a host USB port that can recognize the phone.

Tethering
I use FoxFi or PdaNet is the same. And not require Root.

I got this same letter two or three years ago. Idk but it think they are trying to scare ppl in to the new plans. I regularly use more than 5GB a month without tethering.
Sent from my HTC One X using Xparent Green Tapatalk 2

I got a letter and called them and they are using this as a way to generate more money.

Carriers selling "Unlimited" data, but limiting it to specific devices.

Hey guys...
How are carriers able to limit what my devices get "unlimited" data and what don't?
For example... I'm able to use my phone's Internet as much as I like with no datacap. But as soon as I tether it to a tablet or a laptop... I can only use 5 gb a month.
How do they know what device is using what and is there anything I can do about it? Also, why do they care so much if I use my tablet vses my phone? The only difference between the tablet and the phone are a couple inches of screen space....

Because they're cell phone service providers, not ISP's. People try to use their phone as their only source of internet and if they gave unlimited tethering to everyone they would be losing money.
Sent from my LGMS631 using Tapatalk

Stackexchange questions/47819/how-can-phone-companies-detect-tethering-incl-wifi-hotspot
I learned a good amount from the best answer as far as the "how they do it" goes, but I know that on a lot of phones, rooting seems to remove all carrier bullsnap involved with tethering. If that fails, I gather from that SE post that taking it a step further and installing a custom rom could also help.