3CxPhone für HTC Desire mit 3G

I have alredy installed the app 3CXPhone on my HTC Desire and work perfect !!!!!!!
I have now a questions regarding the 3G. I need to use my voip account most of the day with a 3G connection.
I dont' have for the moment a flat data subscription with my mobile phone provider but only 250MB per month.
When 3CXPhone is always connected with 3G how many MB per day do I need? And for example, how many MB I need for an incoming or outgoing call of 5 minutes???
Thanks for your help.
Toni

PS Sorry mein deutsch zum schreiben ist nicht perfekt, darum ich schreibe in englisch. Aber Deutsch sprache ich kann gut lesen

3CX-Team schrieb:

i can break this not as deep down but 1 second of talk are 80k/s down and up.
Idle is next to nothing.

so 60x5x80/1024= 23MB for a 5 min call what i equal to 230MB for 50 min conversation.

Zum Vergrößern anklicken....

Thanks for your answer.
.....and always stay online in standby?