What exactly does turning off Data Roaming do?

Living in SK, Canada IPhone 4 under Sasktel. Okay so when I go to work located near the boarder occasionally I get a your now US roaming chargers messages. Does turning off data roaming remove all roaming charges like phone calls, messages, etc or just email and Internet like it says? I'd hate to be billed just because I'm too close. Just been turning off all network connections at work so far and data roaming is usually off anyway.

I leave roaming off, that means you use only your carriers network.

You can try turning off the roaming connection and use the normal connection but it won't be possible to use the settings as such for long at normal rates either

this is how the mobile networks work

the mobile networks as we knows retrieves signal from towers, as we travel the signal travels with us and the signals are retrieved from the nearest tower of the network provider

So, obviously when you reach the border, you network will access the nearest tower and if it is out of border, then yes you will be asked to change to roaming settings to make use of the services

if you have the option of using a Wi-fi then try that because you can't really use roaming functions at normal costs when you are roaming unless you have put a separate plan for it