The xyz company has two offices, one in chicago, and a brand new office in pittsburgh. to connect the two offices, they will need a dedicated line, probably leased from the phone company. what type of network will they be implementing to connect their two offices?

You would want to get a broadband internet based phone that's based off a Linksys modem system. A multiple line phone per employee/contractor with voice mail capacities would be a must. For contracted employees (those who work for the business, but are not office-based) need mobile cell phones with the internet, email, and group and individual capabilities so they can be reached easily.