Hacker News Reader

Comment by hitovst | Hacker News Reader

A friend of mine uses AT&T and they shut off service to the SIM saying it was due to AT&T no longer offering 3G. My friend pointed out that the phone hadn't used anything but 4G, or LTE, in the last few years, and the phone didn't require 3G. AT&T suggested it was due to the move to 5G, and the phone wasn't 5G compatible. My friend pointed out that AT&T doesn't offer 5G coverage in the area. AT&T claimed the phone would not work. That was not the case. My friend explained that the phone would work with every band offered by AT&T in the area, and asked the rep to say so if it was simply a matter of AT&T prohibiting the phone. AT&T then returned service to the phone.

Unfortunately, the rep insisted that all telcos would follow suit, and there would be no phones used without 5G compatibility soon.

View on HN

Some of the earliest LTE devices did data over LTE and voice over 3G. Notably this applies to the iPhone 5s does not support voice over LTE - which you commonly see on Android devices as VoLTE. There’s a variety of other devices in the the same situation. The user experience on these devices often does not make it clear that audio is going over 3G.

This has caused many people to get notified of incompatible devices that they thought would work. The devices do continue to work, for now, but as 3G is shut down in a staggered fashion, they’ll seem like they work until the owner tries to make a phone call or realizes they haven’t received a call in a while.

IIRC - It's less voice over 3G and more voice over 2G but done on whatever radio interface you have. A question of using pre-IMS voice call interface vs. using IMS one (which was actually introduced with 3G, but first use for plain voice that most people have seen was WiFi Calling)

AT&T shut down their GSM 2G network in 2017 - the remaining circuit switched calls were going out over UMTS (3G) until the shutdown.

The radio interface used is 3G/4G, but it still used circuit switching instead of IMS (which uses GPRS channel - just like your 3G/4G/5G data - and SIP, iirc)

> there would be no phones used without 5G compatibility soon

With low level of obstruction, the distance range of 5G is half a kilometer. The distance range of 4G is ~30km. 5G covers roughly one fiftieth of the distance of 4G.

If they phased out 4G, people still owning a mobile telephony device would stop receiving service when out of urban areas?

No, 5G have lots of range. Its no worse than 4G, it just depends on the frequencies that the carrier have rolled it out on.

If its rolled out on 26ghz its bad in range. Sub 6 GHZ 5G rollout is as good or better than 4G on the same frequencies.

My carrier have rolled out 5G on 700 MHZ and I am seeing better coverage than their 4G network.

> If its rolled out on 26ghz its bad in range. Sub 6 GHZ 5G rollout is as good or better than 4G on the same frequencies.

Range will be the same, but coverage can technically be a bit lower. This is because the modulation used for 5G uplink (phone to cell site) - OFDMA - is more complex than the modulation used for LTE uplink (SC-FDMA).

This is the same reason you might’ve been in a very rural area and seen 2G. It doesn’t necessarily mean there’s a 2G-only cell tower nearby; just that the 2G signals are more resilient to interference and signal loss.

The downside to that resilience is, of course, much lower complexity, and thus it can carry less binary data.

Is it not just because 2g have traditionally been rolled out on lower bands?

What you're talking about is 5G mmWave. Previous longer frequencies remain usable with 5G. Last I looked into it mmWave was a tiny portion of 5G deployments, as it only makes in very dense urban areas due to the reasons you noted. Of course those mmWave stations presumably still support the longer frequencies because why wouldn't you if the goal is to fit tons of clients onto one station.

>With low level of obstruction, the distance range of 5G is half a kilometer.

Um, no. I regularly connect to a N41 sector broadcasting over 12km away and pull 300-400mbit off it. That's midband 5G, which most consider medium distance.

AT&T is running 3G on 850mhz which they can put a 5G N5 carrier on. This can do that kind of range with obstructions, but is less spectrum so will congest easier like T-Mobile's 600mhz N71 carrier.

EDIT: WCDMA (3G) was always the weakest for coverage. Geographic cell sizes actually shrink as more users connect https://en.m.wikipedia.org/wiki/Cell_breathing_(telephony)

> Unfortunately, the rep insisted that all telcos would follow suit, and there would be no phones used without 5G compatibility soon.

This has approximately zero chance of being true. For instance, all iPhones before iPhone 12 lacked 5G. There's no way AT&T or any major carrier will get away with nuking support for iPhone 11, XS, X, 9, or 8. Probably not even iPhone 7, which still supports the latest version of iOS.

The rep said that 6G was coming soon, and my friend asked if the 5G phones would all be made as worthless as the 4G LTE phones are now. This was one of the reasons given for not wanting to purchase a new phone when their phone still worked with every band AT&T used in the area (which was proven correct when they reactivated the SIM).

Well a famous blogger, was it Randall Munroe? Recorded an extensive conversation with Verizon about their lying about their rates by a factor of 100.

So that works. Verizon's PR had to do damage control on that. That got around. That's how you get them.

Next time record the convo. Record all your convos. They love to tell you black is white over the phone, but then in court, turns out now I am not a lawyer or nothing, but I'm pretty sure they tell them black is black and white is white. American courts work pretty well, especially when it's that clear cut, as far as I see it.

There should be a call app, of course the same people you're talking about are against this it's the telecoms and the smartphone people in bed together (like AT&T and Apple with the original iPhone, openly, and this 5G business) but anyway, the following could still be done. It starts recording the minute "this call might be recorded" sounds. A tiny ML model trained just for that, not connected to the internet, that switches on record when it hears that.

How are you supposed to record calls on iPhones?

That still offers very little explanation about what their motives could be. Do they just want to generate some money, or are there actual concerns about backwards compatibility?

There are only three things that matter: Location, Location, Location.

The higher your resolution is the more you can be sold for.

Personally, I believe that they're worried about a repeat of this incident[0] - and the way they're ensuring that that can't happen is to test and 'certify' all phones before customers are allowed to use them.

Conveniently, they get to charge manufacturers for this certification process; and if consumers don't have a compatible phone, they get to advertise new expensive ones which come with installment plans.

Overall, it's a win-win for AT&T, and a loss for customers.

[0] https://www.theverge.com/2018/6/28/17515464/att-911-emergenc...

Reply on news.ycombinator.com