Telephone relay?

["Ben" <Unilogic_(_at_)_bromarsystems_(_dot_)_com>]

Hi I was thinking one night if this was possible, plus it would help me 
to deal with people with caller id, when you use a calling card it won't 
usually let you through... so I was wondering if I could set a up a bsd 
box as a type of a phone relay... Basically call the bsd's phone number 
up, enter a pin code over the phone, enter the local or long distance 
phone number. Use two modems or more. One to call in on, and the other to 
call out on. I want all this to be able to be controlled by a regular 
tone telephone. If anyone have another way to do this that would be 
great. Just thought it would be sweet to do. Plus helpful to me in my 
travels. 
Thanks,
Ben
ocean_(_at_)_northlink_(_dot_)_net