Auto cut line after 3 minutes of talking??

[GPS]

is there any application that can cut the line after some minutes of talking ?????/

why is that??
in Greece there are a lot of "company connections" with 3 minutes free on every call....
I have a company connection....with 8 numbers on me....
i can talk to them (and they can talk to me) for free all the day for the first 3 minutes
when those 3 minutes expire
i close the connection and recall
So I can talk with my wife,father, friends, for free ALL DAY

I want a program that can count those 3 minutes....and cut the line when this time expires...

I believe it is very easy.....for you symbian programmers