first of all sms has been used on tdma and cdma networks before PCS was even released, to this day nextel doesn't even use pcs yet sms has been a staple in their plans for years. I've sold phones, I know alot about them, trust me.
as far as the monthly service goes yes, I was auctially suprized when I found out there wasn't one, realistically there would be a monthly charge for tower/antenna upkeep and whatnot. now as far as coverage is concerned that would depend on the area, and the number of customers. for example if you live in buttfuck middle of nowhere montana or something then your going to have problems regardless of your server, if you live in new york then your phone's going to work well regardless of where you are (ok, sewers excepted) but the more people that are using the phones the better the coverage is going to be, let me give another example korea, when I lived there for a year in the army my cell phone worked every single place I went (I mean fucken everywhere, basements, subways, every-fuckin-where. why? because there's millions and millions of people in a space the size of the state of indiana, so they can use far fewer towers to cover the space much more efficently.
point being if withmore was a city of 60 million your phone would work in very square foot of the fuckin city (except maybe the sewers) because with so many people in the city their target audience would be everyone.
one last thing: prepaid cellphones-- once again in the us not as popular as overseas, in fact most people from europe don't even realize that contracts exist for cellphones because everyone has prepaid, in america, because of the way the customer base was raised we live in the world of free phones, and contracts, prepaid phones are just starting to become as cheep as regular ones, but overseas...... prepaid is to contracts as contracts are to prepaid here, if they even have contracts.