How to obtain call duration time?

[Krishna Dagli]

Hi,

How do I find out the duration of call on the PC? Assume a
Cell phone is connected to a PC using Data Cable when anyone
dials out using this phone, as soon as it gets connected to
the other end, a program should be fired off on the PC. In
this program I intend to monitor the duration off the call
and perhaps display a ticker with each second. 

I'll really appreciate any help/pointer.

Thanks in advance
------------
Krishna