From some time I noticed that Mtel (my mobile service operation) is using VoIP when I'm calling an Mtel number while roaming.
When I'm calling another operator's number while still roaming, there's no VoIP.
CHEAP BASTARDS. For these prices you can at least provide a decent service - a VoIP call is with bad quality and the callee cannot see who's calling, he sees some service number.
BUT THATS NOT ALL.
The top of the cherry is that when Mtel is using VoIP they clearly cannot see whether the other side answers or not, so no matter whether you make a successful call or not - while you're ringing you get billed. That's not right, is it?!
I found out all that today while checking my bill. Two months ago while in Brno I made a call and was quite sure that I would get billed for that call even though nobody answered.
GOTCHA, YOU CHEAP BASTARDOs
Update: other case of proved cheating:
Mtel made me pay 200 bucks for half a megabyte of internet while roaming. Before that I explicitly asked for the price. It came out that the price is 10 times more and they charge every GPRS session for a full megabyte (with 10 times the prices) without saying it.
Few months ago I caught them billing me for an international call to a friend I haven't spoken with for at least a couple of years.