Your father would like to stay in his industry, which means learning the new scene of cable modems, routers and access points, and etc., that the ISPs are providing now. But he might have trouble quickly getting a similar job working for one of these companies, because they'll suspect his outdated skill set. So he may have trouble learning customer service for these new technologies on the job. I suggest he sign up for one or more of these services at home, and start by delving into the innards of the equipment supplied.
For example, Verizon FiOS creates a cable signal from their big wall-mounted interface box, and sends that to a cable modem. In my case they provided a third-party box from ActionTec; a combination cable-modem, router and wi-fi access point. This product has a detailed manual available on the web, and they provide all the information, so you can manage it yourself and change settings, etc. (In fact, their software is GPL open source!) So he can learn by experimenting, and update the experience and knowledge parts of his resume accordingly.
Hah, he might be able to get consulting jobs helping companies change over to the new approach.