Can you please help advise me on what type of network I need for my new office building that is currently under construction?

I'm building a new office building for my insurance agency. There will be the front reception area and five offices.

Basically we only have one option for internet, local cable company via coax. I need hardwired internet access in each office because we use Vonage phones so the phone has to be plugged into the internet. The main internet will enter at reception desk and that's where the modem will be.

What's the best way to do this? To run ethernet through the walls to each office? That's how we have it at my current office. The cable modem plugs via ethernet to the wall and then we can connect our other computers and phones to the ethernet port in the wall in each office.

Any advice/suggestions? The electrician is there now but said he won't do data lines to each office, that I'll have to find someone else for that. I don't even know where to begin.... I'm supposed to have all of this wrapped up by next week to start insulation and drywall.

What do you suggest?