DVmaker

Here's my situation. I need to setup a small VoIP call center for a small business. Voice mail, call transfer to extensions/external lines, basic menu systems are a must and the system should also be scalable. I saw IVM and Anon but aren't sure which one to use or if i should use both. I do like the idea of having Axon on a Linux box but i see the IVM is only available on a winOS. Can anyone help?