I installed a network once to take an Astra system. I had about 2 days to install the network on all the floors and then the phone guy turned up on the Thursday with his Astra box.
He said, "I have no idea how this VoIP stuff works".
I said, "That's cool, we'll open up Alex and just follow what it says to do".
We pretty much had a working phone system by the end of the day, the phone guy didn't even show up on the Friday, and when the hundreds of people arrived on the Monday to move into their new building it all worked perfectly, apart from about 2 faulty phones.