Can anyone provide a website (preferrably) or a book that gives an overview of VoIP architecture? I'm trying to figure out how to propose a solution of VoIP within an organization that currently uses an old Siemens PBX. Answers I'm looking for are regarding the ability for certain info from the server network to be displayed on a user's PC screen when a call is transferred from an external call center to an internal user and I figured the only way to do that is to install an VoIP system that interfaces the old PBX with a new IP PBX. How logical does that sound? They also want predictive dialing and IVR. (Those features aren't restricted to VoIP though but if a VoIP system provides them too that would be good.) Any thoughts, comments, suggestion, or further questions are welcomed.