Mobile devices has strict bandwidth data plans. You can keep track of network usage bandwidth on Android powered mobile phone using NetCounter app.
This open source software support both EDGE/3G and Wi-Fi network usage tracking. It can send alerts on a counter basis if limit exceeded. You can also export or Import data to & from the SD card in CSV format. Dynamic counters that can be added, modified and removed. “Total”, “Last 30 days”, “Last 7 days”, “Today”, “Yesterday”, “Weekly”, “Monthly” and more are available.