Yes you can, if you want even MORE options like conferencing, voicemail and other pbx functions you can put a linux box between the two of you and really have a decent system. No no its not expensive… get a PC running at around 700 MHZ maybe a PIII with 128 MB of ram on it and you now have a mini telco sittinng in your closet or basement.
If you have some spare bandwidth you can become a service provider for your friends and neighbors…
“Blowing away the smoke and shattering the mirrors of telecom.”
– Jeremy McNamara