Last month my bill was a bit higher than usual, not that much but still, it gave me a warning of that expensive data roaming. For myself, I am living in Austria at the edge to Switzerland and Germany. 2 weeks ago, I went hiking and realized that I was loosing connection all the time (as I was tracking my route with a GPS tracking software, to upload it to Breadcrumbs). I saw the phone then connected to a swiss mobile network, what is dangerous if you have your Android syncing on. There is an option in Android to disallow data roaming, but as I am on a Virtual Network provider (Bob.at) I have to allow this, as I am roaming in Austria on A1, to get it working. So of course my phone downloaded a few bytes during that time and I had to pay those expensive fees. So I was looking on how to prevent this from happening. After some searching in the Android Market, I stumbled upon ‘Real Roaming Alarm’. This App will automatically notify you if you are on a different network and switch to ‘Flight Mode’, so everything will shut down, even the incoming calls. The incoming calls switch off is not really what I want, but as I get notified anyways, I can switch synchronising off by myself and go back to normal mode. Better to be not available for some minutes/hours, than paying crazy fees.
If you know a better app, let me know.