LPT: When you have no cell service (multiple bars of service but nothing works) at a crowded event, turn off LTE in cellular settings. Phone will revert to a slower, but less crowded, 3G signal


can confirm. This happened just a couple months ago.

TL;DR — AT&T is a bunch of assholes for doing this.

Keep in mind 2G was originally deployed in 1997, at a time when internet access for cell phones was extremely limited and required specially-designed pages for it to work. It’s a 20 year old technology. 3G was introduced only a few years after that. Then the industry took a dirt nap on deployment — large chunks of rural America are not LTE enabled. Because of the signal requirements for 3G, in marginal signal areas a cell phone simply might not be able to maintain a connection. 2G is pretty aligned with GSM though — if you can connect to a tower at all, it can service 2G. Which is why some people in the industry boo’d AT&T for doing this.

They didn’t do it for technical reasons: All of these protocols are built into what’s called a ‘stack’. It’s usually a single piece of equipment that handles everything RF for that tower. It doesn’t cost anything to keep 2G in, in much the same way it cost nothing for nearly every baseband chipset for cell phones to have an FM radio receiver. It’s just a sliver of silicon in the corner of some chip buried in the beast. The RF frontend doesn’t care. And it’s being disabled for much the same reason: Forced obsolence or manufacturers and providers trying to force unnecessary upgrades.

Because of the bootstrapping I mentioned earlier in this thread, your phone has to cycle through 2G on its way up to 3G — 3G is a superset of 2G. More bandwidth allocation, frequencies, yada yada. It has to still be in there, sortof. There’s some technical fuckery here you can get around that with but I don’t care to get into it. What you can do, though, is just blackhole anything that tries to send data over a 2G connection. All this connection status data is just collected by the RF side of the stack and crapped out onto what’s basically like your computer today. It does all the decoding and encapsulation, decides what to do, etc. The RF side is dumb. All it does is take the raw data it’s being fed, already predigested with codecs and such, and dumps it out onto the air, and takes whatever it receives, even bogon data (data streams, errors, and other hiccups that just should not ever happen) and feeds it back. The takeaway here is: They’re not doing it to save money on deployments. The equipment going out the door today, new, is still going to have 2G capability. They’re neutering it on the software side of the full stack.

I know I’m making this even longer by adding this but there’s a push now for something called Software Defined Radio. You can actually buy one, you, personally, today. And you can make it do all of this — baseband GSM, 2G, 3G. They actually deploy this out at Burning Man, I think. They weren’t pros so they had to learn a few things along the way about how specifications don’t translate well into how the realworld works. 😀 But they do it. LTE isn’t much of a leap either — the SDRs people can buy today can’t do it only because it’s on a different chunk of spectrum and spread out across several bands. SDRs you can buy today don’t have the spatial timing and resolution required to discombobulate the defrobulator on the heisenberg compensator… okay, I could tell you the truth but it would be fifteen pages of a primer on RF engineering. Let’s just say “Math is hard” and move on. The stacks we’ll have in the industry in a few years will be built on SDR, which means we’ll be able to not just do all of the previous protocols and such, but roll out new ones the same way you do a windows update. Very. Cool.

EDIT: It’s been pointed out that SDRs are capable of this now.

GSM is a very old technology. It does have some deficiencies, which I won’t get into. But there’s no technical reason why a phone bought in 1995 shouldn’t still work today (for GSM handsets). CDMA is the other network, and phones from that era won’t work today. That was the one deployed first in this country, and its initial incarnation was as the giant brick phones you might have seen in some old movies. These were analog, not digital, and worked more or less like a radio on an airplane or a police walkie-talkie does — except the transmit and receive pairs were assigned by the tower. Otherwise, everything was sent in the clear. The old Motorola Startac phones had an engineering mode you could access to reprogram it’s network identifier. Changing that meant you could make your phone look like any other on the network. Cue free phone calls! You could also listen in on other people’s calls through that same interface, I think. If not, people using scanners could punch in those frequencies and hear all the conversations — though it would be a mess because you’d only hear one side of the conversation on each frequency and scanners of that era didn’t come with captain crunch secret decoder rings that matched them up.

Anyway, back to AT&T. They’re doing this basically to screw people who buy the cheap GoPhones. They’ve been trying for years to screw over prepay phones, because a lot of those providers buy network access through AT&T and resell it. Mutter mutter FCC, mutter mutter common carrier mutter. They can’t shut them out. These providers have been rolling in data that count as ‘minutes’ on these dirt-cheap phones, and it’s undercutting AT&T’s offerings for the more expensive ‘smart’ phones with contracts and all that. Shutting off 2G nukes that niche market. No cheap phones means the working poor don’t get internet on their “obama phones”, as republicans would call them. There’s no technical reason to do it. Unfortunately, it screws a small subset of people who already have a rough time getting online just that much harder: Rural users. There’s literally no technical reason for them to have done that. It’s purely marketing fuckery. Our tech can not only continue to provide that service, but we can actually start ‘future proofing’ our networks, after a fashion, so that when it comes time to do a new rollout, we just push a button and all the towers upgrade and start chatting on a new protocol. Your phone will be able to do this too, someday. But it’s about ten years off.

Author: MNGrrl