It's all around you
What? The internet of course: it just managed to evade the constraint of the classic wires and circuits that harbored it in the first place, and now its almost everywhere: through all those devices that generate and connect to the network. Even the name: www – "world wide web" is strikingly accurate.
During the early years of cellphones, their main use was that of letting people talk from mostly anywhere, regardless of distance. Along with the price for the phone, there was also a price, in accordance with how much someone called or was intending to call. Now, it is not hard to get it that there are some ways for you to call for free, or at least cheaper.
To pay for data or to pay for minutes?
By now, when you get an iphone, it is most likely that you also receive a data plan, with additional costs applied if you exceed the provided amount. Considering all the updates that are made, for your programs and games and even the updates for the updating software, operating system, or that really expensively designed AI, that allows people to actually interact with their phone to a certain extent, sometimes with more or less satisfying results, since it tends to get sarcastic, or the requests/settings that people make, are followed a bit too strictly; there is a big possibility of finding a depleted data reserve, if, for example, your updates decide to trigger all at once, and you're not connected to wi-fi, and certain settings are not made.
If the updates don't eat up all your data, there is still a chance that when, you arrive in a place that is sure to have wi-fi, and you just start minding your own business on the internet, only to be later met by a surprise phone bill. It is not hard to rack up huge costs, just imagine you start to carelessly surf the internet, watching all that new hits on HD quality, and too late you realized that the wi-fi was off and your data plan was being used. Furthermore, since the 4G allows many more megabytes to "slip" undetected, there is the chance that you spend 1 or more GB in a single trip to the cafe.
Advantages of calling through wi-fi
Wi-fi calling allows you to use the internet for your calls, with the help of a software, so in some cases, there won't even be a need for you to have a SIM card in your phone, or actual phone services active. That can be considered an advantage, however, it also makes you reliant on the internet.
So, if your phone can make such calls, why not use them to lower the costs?
It's just there in the air
If wi-fi signals would be causing pain, a majority of the modern society's people would be agonizing, since they are everywhere! Soon, according to some projects, even some of the street lighting could be a source of wi-fi. Some buses already have it, and cafe's and parks are getting undoubtledly "covered" by those as well.
So good news if you are using VoIP or any other internet-related means, to stay in touch.
A wider calling range for smaller prices
The habit of using those apps to surf the internet, play, draw, share interests, etc., is clearly spreading as a notable percentage of people are using smartphones. Since getting an app is so easy, why not use them for calls as well. Nalotel provides free app-to-app services, which can come in really handy when you need to stay in touch, long term, without worrying about spending any money. All you have to do is to download Nalo, from magazine play or app store, install it, and voila! Free (or cheaper) calls. Even if you want to reach someone who doesn't have the app installed, you can just use the international calling rates that Nalorel provides, and keep the costs in check.