I think you’re seriously underestimating the size of this job. This is the work of 4-5 people over several weeks to even upwards of a month. PBX alone is a real PITA to get setup and to manage. Then you actually have to train your people on how to use the infrastructure you just setup for them.

Like you said, they’ve been operating one way for two decades and now you’re completely uprooting that on top of having to setup and manage everything.

You’re underestimating this.