Eli5: Why do we need an Internet connection to make video calls? Why can we just do it through the cell towers like a normal call?
In: Technology
Transmitting voice takes very little “space” compared to high quality video. This space is called bandwidth and, in simplification, the bigger the bandwidth the more data you can send.
Modern cell towers are also used for mobile data (internet connection) so technically you can video call through a cell tower.
There are several generations of cell tower signal, 5G is the latest common one. In simplification, newer generations could carry more data but had less range. We keep some of the older generations because they have bigger range, and more importantly, so that older devices are still supported.
Mobile data became a thing in 2.5G (an evolution of 2G but not a big enough difference to be called a generation newer)
I’m guessing you’re referring to internet connectivity over Wi-Fi? The simplest answer is because video takes up a *lot* more bandwidth than audio, and cellular frequencies have limited bandwidth space due to the hundreds/thousands of other people all trying to use the same antennas.
And while there are video compression tricks that allow you to use your cellular connection to watch video via YouTube, Netflix, etc., you’re only downloading the video signal. With a video call you’re no only downloading a video from the network, you’re also uploading a video of your own at the same time, meaning you need twice the bandwidth of someone watching a YouTube channel.
As a result, most providers won’t even entertain the idea of cellular video calls; the network would be overloaded pretty quickly.
What kind of phone are you using that can’t make video calls over the cell towers? Do you perhaps mean “why can’t we do it through the cell towers without using cellular data?” Because you certainly can make video calls without being on wi-fi.
But assuming we’re in agreement on that point, the problem is that carriers have agreed on a standard for how phone calls should work from one device to the other, and how text messages should be sent from one device to another, but there’s no common standard for video calling. So you end up using Facetime, Meet, or another app to make the call because it’s just not something the carrier can do. If video calls were possible, it would need to use a system that was supported by all smartphones and all carriers at once, and it is incredibly difficult to get anyone to agree on that. Also, there is no financial incentive, because carriers would never get away with charging for video calls as all smartphones have apps built in for that.
Because it didn’t catch up. In the early days of 3G internet many carriers advertised video calls that were billed per minute, as normal calls (at least here in Poland). But in early days not much people had phones that supported it, so it didn’t really catch up.
And then in a short span of time everybody had a phone with facetime/whatsapp/messenger/whatever else for video calls that aren’t billed per minute, and if using unlimited wifi at home are basically free.
Carrier couldn’t compete with that, so they’ve just got used to the fact that they’re offering you a data plan, and you use this data for whatever you want, including video calls.
Technically it is possible. Since 4G was fully implemented with IMS in the background there is a technology called ViLTE or Video over LTE but it never really took off. It was replaced by video calls on applications such as facetime or whatsapp. That technology would use network native video capability via dedicated bearer (imagine having your own dedicated lane on highway) unlike these applications which use the standard data bearer that is shared between all people on a single antenna. The main reason why ViLTE never took hold is that app use is much more common since the basic internet is now good enough and you don’t really need to have dedicated resources.
Source: Am telco system architect.
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