Comment Open Source Options (Score 1) 405
We have an Open Source project called FreeSWITCH http://www.freeswitch.org/ that allows you to do this sort of thing with any computer running Windows MAC or most UNIX. It can be paired with traditional phones with a small analog adapter or a hardware telephony card from Sangoma http://www.sangoma.com./ But you could just get a software phone for free as well and play around with it.