Voice-over-LTE: The Reason Why Your Phone May Soon Stop Working | Hacker News Reader

Voice-over-LTE: The Reason Why Your Phone May Soon Stop Working

hackaday.com

Most of the USA is VoLTE-only for a ~year already. For other countries see https://en.wikipedia.org/wiki/3G#Phase-out

No, the 2G network is still running at least for T-Mobile. I happened to check earlier today.

New T-Mobile SIMs haven't been able to work in 2G phones for a bit now. If you have an older SIM that's still active you can use it in a 2G phone but they don't want new customers using non-VoLTE devices on their network. They also haven't invested in expandning their 2G footprint since about 2015 when their network was significantly smaller. The 2G service will be discounted in April.

I happen to have a newly bought T-Mobile prepaid SIM card. It offers limited "high speed data" (4G, 5G, etc) and unlimited "slow speed data" (2G, 3G). Once I ran out of "high speed data", my service was supposed to fallback to 2G, but it doesn't work. I asked why via customer support and the consultant said that they know that it doesn't work, even though they're selling it. Took me 60 minutes on the phone to get to that point. I just gave up. I ended up paying 30 dollars for around 3gb of data and wasting a bunch of time. T-Mobile has been horrible in my limited experience.

You don't fall back to the actual 2g connection. You're supposed to fall back to 2g speeds aka 128kbps or 256kbps. You'll still be connected to LTE towers, just at painfully slow speeds.

Correct, it just feels like it’s not working because almost nothing is designed to function at such slow speeds (HN is one of the good ones though!)

There’s a hidden advantage: you use the phone a lot less when outside. It’s enough for email, chat and a slow map. Could feel both annoying and a blessing at the same time

That would be great, but in my case I am getting no connection at all. Hacker News times out.

In case it actually meant unlimited data on actual 3G, the towers are not going to force downgrade to 3G just because the data plan had ran out. You’ll have to turn off LTE from phone’s settings app.

They're much better than verizon who will just terminate your line with maybe a little bit of heads up.

We found out the hard way when they terminated our line after having a sim card in a non volte phone for about a week, and didn't get the text alert until AFTER the line was disconnected.

> ’The 2G service will be discounted in April.’

The last nail in the coffin for my Motorola Razr V3

4/2/2024 is the planned shutdown.

Even 2 years ago, I got an iPhone 5 from somewhere and found that because it didn’t support VoLTE, no carriers would support a new connection. They would support you if you were already on board for a little while.

Yeah, my carrier forced me to upgrade two years ago when they went VoLTE-only.

One often unexpected consequence for tourists visiting a country that has executed a complete 2G and 3G shutdown is that they won't be able to make voice calls, even if their phone and plan supports IMS (i.e. VoLTE) when at home.

i discovered a month ago that there is "VoLTE Roaming" that phone must support in order to be able to roam. looks like it specific for phone models/operators and not generic

For some reason lots of Android phones (even the Pixel models from Google) seem to use a whitelist approach that is quite restrictive regarding where VoLTE is supported. For example at least up until recently (and probably still the case?) Pixel phones only supported VoLTE in countries that were in the list of countries in which the Google store official sold Pixel phones.

Meanwhile newer iOS versions seem to nowadays have generic VoLTE (and even VoWiFi) support that even works for smaller MVNOs without an iPhone carrier profile (as long as their VoLTE implementation somewhat conforms to standards).

And worse, it differs when roaming. I am aware there are networks where if you are their customer VoLTE works but if you are roaming onto their network it does not work at all. With the exact same device.

I’d have to think that a network that shuts down their 2G network probably allows roaming devices to make calls over VoLTE. All those carriers that don’t allow roaming devices to make VoLTE calls probably have an active 2G network.

There are a lot of interoperability bugs in VoLTE. The best part of standards is that each vendor implements it slightly differently.

Apple tends to hold back a feature until all carriers have blessed it. Apple withholds Carrier Bundles from MVNOs who don’t promote iPhones, so iPhones are more likely to be used on fully compatible carriers. They also have significant market weight so a MNO is less likely to decide they can’t bother to fix interoperability bugs with iPhones.

There’s a correlation between buyers of expensive smartphones and higher ARPU customers which further increases incentive to put in the engineering resources to squash bugs but only for flagship phones. MNOs also have an incentive against improving interoperability as it makes it easier to switch to another carrier (“churn”).

> newer phones like the Samsung Galaxy J3 (2016)

I know we are a more tech savvy crowd but is using a 7 year old feature phone really the best example to make this argument? I imagine that most people keep their phones closer to four years.

I think the sentence before that is more important though I do wonder if that is correct:

    In order to make a VoLTE phone call, your phone, your provider, the receiving phone and the intermediate network providers must all support the protocol.

The receiving phone? WTF?

So I can't use my VoLTE phone to call a land-line in another country? That would be stupid if true.

Meaning that really can't be true.

On the other hand, SIP commonly has issues like one-way calls because all the data channels don't connect correctly. Easy peasy calling landlines though, it just runs through an ATA on the customer side and treats calls as a regular data stream. That's how our FTTH service is moving people from DSL+landline to fiber to feed all their services, including cable.

I'm pretty sure they're confusing VoLTE which only needs your phone and your provider to support it (and provision it, etc, etc, if you're roaming, there's more, etc, etc), and the higher fidelity "HD Voice" G.722.2 codec, which does require end to end support. Your provider might connect your end as HD Voice to a call terminating as POTS on the other end, but I'm guessing probably won't.

That would be the only thing that makes sense actually.

I have various old phones at family members' homes that still speak ISDN or "regular landline" to the respective router. The router used to also connect via ISDN and/or regular POTS to the phone company at various points in time. Nowadays it's actually some sort of VOIP protocol as well and those old phones don't care. Nor should they need to care.

Nor should a caller somewhere on the other end of the world care about that and vice versa what that caller uses to connect to their provider.

If VoLTE doesn't support that, then color me unimpressed and fully against it. Not that I can stop it, but it would be completely utterly stupid ;)

> I know we are a more tech savvy crowd but is using a 7 year old feature phone really the best example to make this argument

The J3 isn't a feature phone. https://en.wikipedia.org/wiki/Samsung_Galaxy_J3

Sorry I meant budget phone. Compared to the s7 which also came out the same year. https://en.m.wikipedia.org/wiki/Samsung_Galaxy_S7

it's exactly the kind of device I'd base an argument on. The machinations of the mobile device and telecom industry are adversary to a majority of consumers. I don't want to buy a phone every 5 years to continue to make at best 32-64kbit/s bitrate calls to mom and pop.

One change I noticed from LTE to VoLTE is that the line now goes silent when the coverage gets spotty. Before, you would hear bits and pieces. The benefit to that was that even if you were talking you could hear little bits coming through (including silence) and you would know that the other person probably couldn't hear you well. Now you just hear nothing, and have no idea.

> even if you were talking you could hear little bits coming through (including silence)

Do you mean comfort noise by any chance? https://en.wikipedia.org/wiki/Comfort_noise

I don't see why that strategy wouldn't work for VoLTE, but I don't doubt that some implementations might not have bothered.

I don't know if it was natural or artificial. I just remember turning of VoLTE after the rollout first happened, since I preferred the old way. Now there is better coverage where I live, so it's less of an issue.

My favourite thing is how they’re doing it all over again with VoNR (5G)!

Why was voice a mandatory feature for 3G but everything since has been such a mess?

Because cellular standards up to 3G were designed to support circuit-switched voice lines, i.e. you would get a dedicated slice of network resources for your call. That meant the voice interface had to be built into the base standard just like data communications. 4G and 5G treat voice traffic as packet data (not quite like other data, I believe it gets slightly higher priority) so VoLTE/VoNR is just running a data application on top of the 4G/5G data link. That means you can specify the voice connection seperately and many carriers take advantage of that to do things their own way (to the detriment of consumers).

I'm feeling this pain right now. I was forced to switch to my backup phone after my main one broke. Data is okay over LTE, but it doesn't support VoLTE, and calls over 2G is miserable. Connection is super spotty unless I take the call outdoors, and even then, quality isn't great. Couple that with T-Mobile shutting down 2G in April 2024, and guess who's forced to purchase a new phone just to keep up.

I'd recommend buying a phone from Tracfone (or one of their sub-brands) with a bundled year of service, and then unlocking it after 60 days. They frequently have sales of those bundles for $100 or even less. You should be able to take it to T-Mobile if the model isn't proprietary to Tracfone/Verizon (though you will be stuck with the Tracfone customized firmware). According to this page which tracks prepaid phone deals, QVC and HSN both have Tracfone bundles on sale with lower-end Samsung phones for around that price, and even one with a Pixel 6a if you're willing to spend a little bit more: https://prepaidcompare.net/deals/

My main concern with these higher frequency connections is that they require a lot more power to run. So we can’t have phones that will last weeks without charging.

Turn off cellular and wifi on your phone. I bet it won’t last more than a few days anyway. I don’t think radio power consumption is the barrier keeping us from weeks-long battery life.

I actually did this with my old Android phone earlier this summer after getting my new one. Under normal use I had to charge it every day, with Airplane Mode on (and, granted, not using it) the battery lasted like 3 or 4 weeks.

> and, granted, not using it

Well sure, then it's like a tablet in standby, which similarly can last a month or so.

But it's not going to last more than a day or two if you've got the screen on, playing games, watching movies, using apps offline.

Installing a version of Android without Google Play Services running constantly in the background effectively doubles handset battery life in my experience. Disabling radios can do that again if the device is rarely used.

Slightly offtopic but related: One of my mobile providers supports configuring public (non firewalled) IP addresses for mobile devices and when choosing that option my phone battery drains very significantly faster than otherwise. I suspect it's because all the random packets that arrive every second or so on the public interface (when NAT and firewall are disabled) either cause the radio to use a lot more battery or prevent the CPU from going into sleep mode (or both of that).

I've been wondering about that! A long time ago, I had a phone plan like that as well (in fact, a public IPv4 was the only option), and I was wondering if random port scanning would eventually use up all of my data allowance.

Turns out stateful firewalls aren't just a security factor on mobile internet connections.

I've luckily mostly been on unlimited data plans, so I don't know about it using up your data, but I guess it would? Your device is sending and receiving data. I don't think there's a distinction for externally made connections, otherwise vpn tunnels would have been really popular.

I did have an experience with my phone being suddenly used by random internet users. I had ampache running on my n900 (maemo/debian-based) and somebody found it on the internet and started streaming my music. :D I had a higher-than-normal amount of battery usage for a few days so I decided to see what's using it and discovered that my music was being played and downloaded.

That reminds me of when I had a computer with spinning rust hard drives on my desk in grad school. At some point I was trying to focus but there was a periodic, roughly once a second hard drive noise that was driving me nuts. Went through the usual suspects at the time like the background locatedb updater, and eventually ended up finding that some bot was trying to ssh login once per second going down a list of passwords, and the errors were being logged to disk. Need I mention the computer had a public IP address?

So you go from 1 to 4 days. Still not “weeks” :)

> My main concern with these higher frequency connections is that they require a lot more power to run.

That's generally not true.

What does require more power is a higher data rate (which is often available only on higher frequency bands, due to there being more bandwidth), but there shouldn't be any meaningful difference for a constant data rate voice call across bands.

If anything, higher frequencies usually imply a denser network of base stations (since radio propagation is somewhat worse), which means your phone needs to transmit less in the end since there's less distance to cover.

For example, GSM at 900 MHz had a maximum mobile EIRP of 2W, while at 1800 MHz it was only 1W (at the same channel bandwidth).

lxgr explained why this isn't really the case on the radio side. What you're actually experiencing is you went from using a phone that had no backlit screen, no apps, no OTA app updates, no push notifications, no AI-enhanced photos, and a toy CPU to a full-fledged computer in your pocket.

Battery usage and frequency have practically no correlation. I've got HF gear (things running at just a few MHz) that use car batteries to run a few hours. I've got 2.4GHz stuff designed to run off practically a watch battery and for their use case last weeks.

And either way phones running on 4G LTE or 5G are largely using the same frequencies as before. Few phones actually connect to those ultra wideband networks for any notable percentage of the time. Most of the time they're connecting to 4G/5G towers operating around the same older GSM bands. Those earlier StarTAC phones and the Nokia 5110 ran at ~800-1900MHz. A modern 5G phone on T-Mobile US (Band n71) will operate on 600MHz. On your logic, a modern 5G phone on T-Mobile should work much longer than many older phones.

Reply on news.ycombinator.com