Where I live, in the UK, someone calling your mobile phone is free. You have to be very desperate or in bad position not have a fixed line phone too. I need a mobile number to get a job but then I have got a PhD :-) Understanding some mathematics[*] did matter and my life time experiences did not.
The cheapest mobile phone is 10p/min to landlines and the same network and fixed lines, and more elsewhere. Fixed line phones are much cheaper and the rates are more like 1p/min and free at weekends, which is a better deal even after you include line rental.
3G which is cheaper to use that 2G but much more expensive to call. You can only get a 3G phone at sensible price with an expensive contract which carries very high commission. Even with the cheapest pay as you go deal the handset is subsidised.
Having seen the phone salesmen's price sheets I know expensive contracts have commission in the £100-£300 range ($150 to $450). This pays for quite a fancy phone with some room to spare.
The cheapest the high street offered me was £40 ($60) for a phone tied to a network. An unrestricted version that model costs them only £20 ($30). The profit margin here is clearly significantly more than 100%.
A decent fixed line phone, with no contract, costs under £10 ($15).
Most phones can be untied, or bought tied to a network of your choice. Apple invited bids for the privilege of supporting iPhone users, and it is probably almost impossible to use any other network. (Hacking your phone could invalidate its license to use regulated mobile phone frequencies,)
[*] Many people think they understand the mathematics I used but actually dont. When the mathematics is used in anger the difference becomes obvious.