You can connect to your wifi at no extra cost and connect to wifi hotspots when you are out and about but if you go to areas where there is no wifi available you will need a SIM card with a data plan, which does cost
You could choose to only use the internet in areas where free wifi is available. You would only pay if you were using data through your mobile network.
In fact it’s really the opposite.
As above, it’ll do “ internet” by default.
You have to pay extra to use is as a phone (and only then if you decide to use a call provider that doesn’t require a mobile number)
I have a mobile phone which I use without the internet, basically to send and receive calls, and send and receive texts. I do not have a mobile contract with a phone company. I use "a pay as you go" system, with a card I top up when needed. I think I originally had to buy a sim card. I bought one from Virgin who provides my internet for the house.
Hope this helps.
You have a smartphone with no SIM card
It can do internet via WiFi.
You want to make calls (unless you use something like facetime)you need a SIM card.
I can’t make make it much clearer. But it’s a side issue and I’m sorry I mentioned it now :-)