While working for ICS Ltd the company relocated its offices half a mile down the road to a building they had purchased.
I successfully produced plans for the move of the entire network from one site to another, whilst in the beginning the directors did not full understand the plans i had produced and on a few occasions I was forced to redesign some of the planning I still was able to move everything.
I achieved this by using XenServer Virtuallization platform to make a copy of all physical machines, to free up some servers, I then took these servers to the new site and replicated services between sites, on the actual day of the move when the phone lines and PBXs and everything was turned on there where a few tweaks here and there but on the whole I was able to move the complete site with minimum down time and impact to its clients, who I am understood to have not noticed little or no impact to there message taking systems.