First of all, nobody will understand what does a cell have to do with a mobile ("mobilni"). If you're in a cell, you don't move much. Or is this some biotech thing?
When cell phones were introduced in the nineties, nobody ever said "cell". That kind of description was never publicized. It's the mobile, period.
Second, and more important, is the list of specific properties of the mobile system.
- Recipient of the call or message pays nothing. Maybe they did early on, but that's long forgotten. Nobody gets angry if you answer with just "ok" - doesn't cost them a para.
- Most of the people own their phones, and can switch providers as they please. The pressure is mounting to force them to enable you to carry your number with you, not likely to happen soon. The main reason people stick to their provider is the identity the number carries. There's a lot of incentive from the providers to get as many people as possible to switch to postpaid; fancy shmancy phones are sold at less than half price if you only dip that pen in your blood and sign a 2-year contract.
- UPDATE, august 2011: the portability of numbers is supposedly on starting last month. The law which forces operators to allow it came to force on 1-I-2011, but it took them half a year to actually do it. Last I heard, they are testing the equipment. We'll see.
- Adding minutes to your phone can be done in several ways. You can do it at an ATM - swipe your card, enter your phone number, enter amount, done. You can do it online at your bank's portal. Or, the simplest, you can just pay at the nearest kiosk, tell the clerk your number, and she types the amount and sends the automated message to your provider, and you usually get a message before she prints the receipt. Not all kiosks can do this, but it's easy to spot one, as they have providers' stickers in their windows.
- there are many things you can do from your phone. You can pay for parking by sending your license plate number to a number displayed at the gate; you can vote for anything on TV that organizes a poll; you can donate some of your credit to any worthy cause which publishes a number to call; you can pass some of your credit to anyone you like - even in a different network (haven't tried that, but I've heard a long explanation of how it's done). All that comes from your prepaid amount, or you will be billed for that. The cell phone is a purse.
- UPDATE, november 2012: now you can pay your electricity bill via a cell phone.
- UPDATE, january 2013: now there's a SMS money order, where the recipient can get the money within the hour. Here's how it goes: you appear at the post office with the cash, tell the clerk your number, recipient's (cell phone) number, and you fork out the cash you're sending, plus some fee, and get a receipt. The clerk sends a SMS to the recipient. The recipient gets a message from the post office, takes the cell phone and his ID to the nearest post office, shows the message to the clerk, gets the money, signs the receipt. No papers are traveling anywhere, there are only the two receipts as the trail.