When I Joined Hello Telecom I was asked to look at the servers in the core data center and see if I could find any improvements etc.
I had a look and quickly found that the developers need servers to test with and also found that if one of the core voice servers failed it took out half the client base.
my proposed solution was to buy 3 Physical Servers with good specs, install Citrix XenServer on and migrate the other physical servers on to them and to discontinue them.
This would have allowed all the servers to fail and for the voice servers running on top of the XenServer to automatically move over to another server and prevents down time to the client.
This would also have allowed the developers to put up servers quickly for testing and for roling out new services with out buying additional server hardware, as the company grows they just need to purchase 1 server at a time with XenServer on it and load balance the voice servers across them.