We are a hosting company looking to get in the VOIP market. We want to offer a virtual PBX to our customers where it is then directed to the correct IP phone. Our business model is the same really as 8x8 virtual offices http://www.packet8.net/about/virtual_office.asp Obviously as a hosting provider we are in the national telecommunications data center and have access to several server and router options What is the 1. Best way 2. Cost effective. All from the ground up what would you the experts do?