The traffic counter for my account seems to work incorrectly:
The current consumption to date is 2305 minutes - 4.6 GB. That is 2 (TWO) megabytes per minute!
I mostly use g729 codec for my extensions in pass-through mode and g711 (probably) for callback. But even if g711 consumes 80kbit/s (or 8kbytes/s) the traffic should be 480 kbytes/minute at maximum.