My dad mentioned a co-worker suggested using a device, that might use CDMA to route calls through IP to save costs on a certain overseas project we're on- since our home base is quite far from there. I've never heard of such a device, so if it does exist, I'm wondering, if it's specific to particular ISPs, or if you can just pick one off the shelf, plug it into an arbitrary Internet connection, and make calls using it and a cellphone of some sort?

As you can tell, details are sketchy, so... if such a device doesn't exist, saying so might be a right answer ;)