eli5 Why do internet calls such as WhatsApp sound clearer than normal cellular calls?
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Internet calls are a much newer standard. Part of this is the ability to transmit relatively better quality audio, which may vary depending on the codec used.
This is similar to how a VHS has worse quality than a DVD.
Because youre getting a steady connection from a few feet away as opposed to getting a signal from a cellular tower that isnt within 5 miles of you.
Cellular calls have always been made to be as lightweight as possible due to the limited bandwidth of early phone networks.
Some reasons this has remained: It’s good enough, it’s stable, and it has a much greater range (sometimes when you’re out in nature you might only have a bar or two of reception but no internet).
However, nowadays many mobile phones have a VoIP setting which lets you make calls over the data network instead (if both phones have it activated, I’m pretty sure) which should sound much clearer.
You may think that is true because that is all you have seen of the internet. But… There is a concept called “Quality of Service” (QoS).
The Quality of Service for phone calls is “shaped” differently. So where “the internet” focusses on not losing data (but you may have higher ping or ping differences), phone calls focus on low ping and low ping differences (jitter). That low ping and low jitter QoS is expensive. This results in phone companies making the phone call noisy (“low bandwidth”) in order to keep costs at bay.
These days, first world countries have pretty good internet with low ping and low jitter.
The short answer is because they use more bandwidth, i.e more of the audio frequency range.
The longer answer is that the original phone standard came about in a time of more technical limitations, the bandwidth of the audio was from 300hz to 3000hz only, and that carried on to the first cell phones too but they later increased the upper limit to 6000hz.
Internet calls don’t need to have those bandwidth limitations. And they use more modern codecs to turn the audio into binary data, and more modern error correction techniques to fix any incorrect packets of data during the transmission process. Service providers also have the benefit of using their own standard and changing it as often as they like. Cellular standards move more slowly in comparison, and require lots of international cooperation to create or adjust.
Phone calls often get routed at some point through a network designed to work with your grandma’s rotary telephone. They may be re-converted multiple times (losing quality) and they have to stick to standards that others also support.
It’s getting better with WiFi calling, 5G etc., but for example the 4G standard which is still widespread has been deployed in 2009 and developed well before that.
Whatsapp only talks to Whatsapp, and sends the call as data over the Internet. Introducing a better way to send audio (a better codec) can be a matter of one engineer implementing it, and a week after it’s launched 90% of the users will be able to actually use it as their apps updated. No years stuck in standards bodies to discuss what to implement in the next generation that will come out in 3 years and be common in 5-10 years.
Everybody also makes a tradeoff: use more data and sound better, or use less data but sound worse. Historically providers wanted to cut costs by skimping on quality, but with modern data packages it doesn’t matter as much. That’s also why a call where both sides are on wifi may sound better than a call where both use mobile. Wifi tends to be unlimited so WhatsApp cranks up the quality, whereas if you’re on mobile they may assume that you prefer to have a bit lower quality to use less data.
I do like the absence of echo cancellation and noise reduction in regular calls compared to most voIP services. I have a Mumble/Murmur server when a friend and I really want clear sound.
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