I was working from home (we had no offices yet) and my cable Internet got cut off. My only back up was a serial cable to a 2G Nokia 9000i. I had to re-encode a chunk of the music catalog at 8kbps so I could test it from home before I pushed the code to production.
Psychoacoustic compression is a miracle.
BTW, an interesting thing is that some/most carriers allow you to use CSD/HSCSD over 3G these days, and you can establish data CSD connection between two phone numbers, yielding essentially a dedicated L2 pipe which isn't routed over internet. Can have much lower latency and jitter if that's what you need. Some specialized telemetry is still using that, however as 3G is slowly getting phased out, it will probably have to change.
Still have an entire territory where everything is satellite fed (Nunavut), including its capital.
> Northwestel, one of biggest internet service providers in the North, said it provides broadband service for all Nunavut communities using Telesat's Telestar 19 VANTAGE high-throughput satellite. After the satellite was deployed in July 2018, Northwestel said it would significantly improve broadband connectivity in the territory, increasing speeds to 15 megabits per second.
https://www.ctvnews.ca/sci-tech/efforts-underway-to-improve-...
Interestingly, the same satellite (but different transponders) probably supplies internet to a good chunk of transatlantic voyages between US/Can and Europe: https://www.telesat.com/wp-content/uploads/2022/11/Telstar-1...
> The only app that I am always impressed with is WhatsApp. It's always the first app to start working after a reconnect, the last to get any traffic through before a disconnect, and even with the latency, calls feel pretty fast.
The 200ms is telling.
I bet that WhatsApp is one of the rare services you use which actually deployed servers to Australia. To me, 200ms is a telltale sign of intercontinental traffic.
Most global companies deploy only to at most three regions:
* the US (us-east, us-central, us-east+us-east)
* Europe (west-europe),
* and somewhat rarely far-east (meither us-west or Japan)
This means that places such as south Africa, south America, and of course Australia typically have to pull data from one of these regions, which means latencies of at least 200ms due to physics.
Australia is particularly hit because, even with dedicated deployments in their theoretical catchment area, often these servers are actualy located in an entirely separate continent (west-us or Japan) and thus users do experience the performance impact of having packets cross half a globe.
So, I used to work at WhatsApp. And we got this kind of praise when we only had servers in Reston, Virginia (not at aws us-east1, but in the same neighborhood). Nowadays, Facebook is most likely terminating connections in Australia, but messaging most likely goes through another continent. Calling within Australia should stay local though (either p2p or through a nearby relay).
There's lots of things WhatsApp does to improve experience on low quality networks that other services don't (even when we worked in the same buildings and told them they should consider things!)
In no particular order:
0) offline first, phone is the source of truth, although there's multi-device now. You don't need to be online to read messages you have, or to write messages to be sent whenever you're online. Email used to work like this for everyone; and it was no big deal to grab mail once in a while, read it and reply, and then send in a batch. Online messaging is great, if you can, but for things like being on a commuter train where connectivity ebbs and flows, it's nice to pick up messages when you can.
a) hardcode fallback ips for when DNS doesn't work (not if)
b) setup "0rtt" fast resume, so you can start getting messages on the second round trip. This is part of noise pipes or whatever they're called, and tls 1.3
c) do reasonable-ish things to work with MTU. In the old days, FreeBSD reflected the client MSS back to it, which helps when there's a tunnel like PPPoE and it only modifies outgoing syns and not incoming syn+ack. Linux never did that, and afaik, FreeBSD took it out. Behind Facebook infrastructure, they just hardcode the mss for i think 1480 MTU (you can/should check with tcpdump). I did some limited testing, and really the best results come from monitoring for /24's with bad behavior (it's pretty easy, if you look for it --- never got any large packets and packet gaps are a multiple of MSS - space for tcp timestamps) and then sending back client - 20 to those; you could also just always send back client - 20. I think Android finally started doing pMTUD blackhole detection stuff a couple years back, Apple has been doing it really well for longer. Path MTU Discovery is still an issue, and anything you can do to make it happier is good.
d) connect in the background to exchange messages when possible. Don't post notifications unless the message content is on the device. Don't be one of those apps that can only load messsages from the network when the app is in the foreground, because the user might not have connectivity then
e) prioritize messages over telemetry. Don't measure everything, only measure things when you know what you'll do with the numbers. Everybody hates telemetry, but it can be super useful as a developer. But if you've got giant telemetry packs to upload, that's bad by itself, and if you do them before you get messages in and out, you're failing the user.
f) pay attention to how big things are on the wire. Not everything needs to get shrunk as much as possible, but login needs to be very tight, and message sending should be too. IMHO, http and json and xml are too bulky for those, but are ok for multimedia because the payload is big so framing doesn't matter as much, and they're ok for low volume services because they're low volume.
When I was IT person on a research ship, WhatsApp was a nice easy one to get working with our "50+ people sharing two 256kbps uplinks" internet. Big part of that was being able to QoS prioritise the XMPP traffic which WhatsApp was a big part of.
Not having to come up with filters for HTTPS for IP ranges belonging to general-use CDNs that managed to hit the right blocks used by that app, was a definite boon. That, and the fact XMPP was nice and lightweight.
As far as I know google cloud messaging (GCN? GCM? firebase? Play notifications? Notifications by Google? Google Play Android Notifications Service?) also did/does use XMPP, so we often had the bizarre and infuriating very fast notifications _where sometimes the content was in the notification_ but when you clicked on it, other apps would fail to load it due to the congestion and latency and hardcoded timeouts TFA mentions.. argh.
But WhatsApp pretty much always worked, as long as the ship had an active WAN connection.... And that kept us all happy, because we could reach our families.
It's not exactly XMPP, it started with XMPP, but XML is big, so it's tokenized (some details are published in the European Market Access documentation), and there's no need for interop with standard XMPP clients, so login sequence is I think way different.
But it runs on port 5222? by default (with fallbacks to port 443 and 80).
I think GCM or whatever it's called today is plain XMPP (including, optionally, on the server to server side), and runs on ports 5228-5230. Not sure what protocol apple push is, but they use port 5223 which is affiliated with xmpp over tls.
So I think using a non 443 port was helpful for your QoS? But being avaialable on port 443 is helpful for getting through blanket firewall rules. AOL used to run AIM on all the ports, which is even better at getting through firewalls.
I once got asked "what was a life changing company/product" and my answer was WhatsApp - to slightly bemused looks.
WhatsApp connected the world for free. Obviously they weren't the first to try but when my (very globally distributed family) picked up WhatsApp in '09/'10 we knew we were onto something different. Being able to stay in touch with my brother half way across the world in realtime was very special. Nothing else at the time really competed. SMS was expensive and had latency. Email felt clunky and oddly formal - email clients don't feel "chatty". MSN was crap on mobile and you both had to be online. Ditto for Skype. For calls we even used to do this odd VOIP bridge where you would each call an endpoint for cheap international phone calls.
Meanwhile in 2012, I was able to install WhatsApp on my mum's old Nokia Symbian feature phone, use WhatsApp on a pay-as-you-go sim plan in Singapore communicating over WAP. The data consumption was so low I basically survived 2 months on maybe 1-2 top ups. Compare that with the other day where I turned on roaming on my phone (so I could connect to Singtel to BUY a roaming package) and my phone passively fetched ~50+ MB in seconds and I was hit with 400SGD of data charges (I was able to get them refunded)
I am very grateful to all the work and thought WhatsApp put into building an affordable global resilient communication network and I hope every one of the people involved got the payout they deserve.
Now (in 2024) have you tried Delta Chat?
I did once think whether a client could abstract over IMAP to build to build a WhatsApp-like UI/UX so clearly other people have thought the same.
Although I will confess I'm no longer really looking for a new chat experience...
How is the latency is for Delta Chat?
Do you know why there is a 4 device limit? I run into this limit quite a bit, because I have a lot more devices.
And... Why is there is WhatsApp for most commonly used devices, but iPads?
I was frustrated by this a while back, so I asked the PMs. Basically when investing engineering effort WhatsApp prioritises the overall number of users connected, and supporting iPads doesn't really move that metric, because (a) the vast majority of iPad owners also own a smartphone, and (b) iPads are pretty rare outside of wealthy western cities.
For iPad, I think it's like the sibling notes; expected use is very low, so it didm't justify the engineering cost while I was there. But I see some signs it might happen eventually [1]; WhatsApp for Android Tablets wasn't a thing when I was there either, but it is now.
For the four device limit, there's a few things going on IMHO. Synchronization is hard and the more devices are playing, the harder it is. Independent devices makes it easier in some ways because the user devices don't have to be online together to communicate (like when whatsapp web was essentially a remote control for your phone), but it does mean that all of your communications partner's devices have to work harder and the servers have to work harder, too.
Four deviced covers your phone, a desktop at home and work, and a laptop; but really most of the users only have a phone. Allowing more devices makes it more likely that you'll lose track of one or not use it for long enough that it's lost sync, etc.
WhatsApp has usually focused on product features that benefit the most users, and more than 4 devices isn't going to benefit many people, and 4 is plenty for internal use (phone, prod build, dev build, home computer). I'm sure they've got metrics of how many devices are used, and if there's a lot of 4 device users and enough requests, it's a #define somewhere.
[1] https://www.macworld.com/article/668638/how-to-get-whatsapp-...
https://blog.cloudflare.com/bandwidth-costs-around-the-world
Most global companies (at least the US-based ones) have deployed in India, where I'm at right now. I suppose a billion people online is too big of a market to ignore (or not; I really don't know). Or there are services that I'm completely unaware of that's not in India.
Internet's pretty fast as well. Much faster than a certain conspicuous European country you'd expect to have fast internet ;)
There may be a setting to turn a browser back into a dumb wget visual displayer.
With wget it sends you the source you actually requested and doesn't try to get clever (stupid). Google likes WebP so that means everyone needs to join the WebP cargo cult even if it means transcoding a lossy format to another lossy format.
And yeah, most of the internet works very badly when you drop the network all the time...
Which provider are you with? Vodafone is still dead in large parts of the U-Bahn, but I know that one of them works much better.
I believe someone published a map of the data coverage of different providers on the berlin ubahn, but probably outdated now
I'm with sim.de which I believe is essentially an O2 reseller (apn references o2)
Summary: since 2024-05-06, users of all networks also get LTE in the U-Bahn thanks to a project between BVG and Teléfonica (not surprising that Teléfonica deployed the infra because they had the best U-Bahn LTE coverage beforehand)
So… you can expect apps developed by engineers in London to get much worse on slow internet in 2025. :-)
Wifi inside the trains involves much more work, and to get them to ALSO be seamless across the entire setup - even harder. Easily 10x or 100x the cost.
It's sad, because the Internet shouldn't be that bad when the network drops all the time; it should just be slower as it waits to send good data.
On the London Underground it's particularly noticeable that most apps are terrible at handling network that comes and goes every ~2 minutes (between stops), and which takes ~15s to connect to each AP as a train with 500 people on it all try to connect at the same time.
In Australia you're just 200ms from everything most of the time. That might not seem like much, but it really highlights which apps trip up on the N+1 request problem.
The only app that I am always impressed with is WhatsApp. It's always the first app to start working after a reconnect, the last to get any traffic through before a disconnect, and even with the latency, calls feel pretty fast.