It is interesting. I didnt know that this can be done.

I come across this application that the java app works in the background and routes the call to voip provider-> a certain number,
so it does not change user's telephoning habit.

Even the appliction decides how to make a call - using the SIM to make the call or do a callback depending on the which is the best rates.

Do you guys have any idea how to do this? have tried to search, so far not so lucky.

Thanks in advance.