Question : Cisco Phone Systems

Hi , we are currently have an Avaya phone System in place. Our last 2 telco guys got fired. I am on the network side and have been thrown to this area. I have no clue from phone systems. The project i am expected to complete is to replace the Avaya system with a cisco phone System. We do not have VoiP but we will have ( if i am still there) once Cisco takes over. Anybody has any idea where to start ?  How can i get some white papers and even some links that epxlain how everything works ? i.e why do i need a cisco call anager and how everything is set up etc...
Any ideas ?

Answer : Cisco Phone Systems

Yes the CCVP study book explains things in great detail and should build on your networking knowledge.
It is the basis of how to set up a voice network
Greg