We've come a long way with modern IP based phones.
Not so long ago you were able to drop aging hardware phones systems with the spagetti of wires for IP network based phones. And now we've went a bit further with virtualized PBX systems and cloud based PBX systems.
The great thing about these virtualized phone systems is the ease of deployment and recovery if things go wrong. Drop your virtual phone system onto a new virtual server and you are back up.