In your country?
I was recently on business trip to a El Salvador and i was impressed with their cellular telephone laws. Here are a couple:
Only the originator of the call pays
Meaning, that if User A calls User B, only Users A's minutes are depleted. Makes sense, here in the US both user's minues goes away, effectively charging double for a single phone call.
If you call from a land line to a cell, an additional charge is placed on the land line, the cell phone user talks for free.
No charge for voicemail pick up
Its considered part of the service
No charge if the person's voice mail picks up
If you call your friend and the voicemail pick up, you are given 5 ring tones then you are adviced that after the beep you will be charged for the call, you can hang up and not be charged (or minues taken off) if you choose not to leave a message. In the US you get charged if the persons voicemail picks up.
Mind you that these are laws and not up to the cell providers. This has resulted in an incredible numbers of handsets and operatrors in the country.
So.. how does it work were you live?