I have already come across a bunch of apps that allow caller id spoofing - they are either non-free or play and add. and have other frills like voice changing etc. I am not interested in any of those features.

What i'm basically looking for is something that can practically change my outgoing caller ID more or less permanently - i do not want to launch an app first in order to make an outgoing call.

I am trying to make my iphone set the outgoing caller id to my google voice number so that i don't have to give out two numbers to all of my contacts (my at&t iphone # as well as my google voice #)
I've noticed that android phones have this option (once you have google voice installed) where any outgoing call you make, you have the option to pick which number you want to call 'from'.

if this is not the right place for this, please point me to the right forum where i can post this question