There is no such thing as "underestimation" in customer service.

You may work for a major ISP/Telco. You may be working with DNS, VoIP, and other fancy acronyms. You may associate with other technicians, both within and outside your corporation of employment. But there is one thing you just simply cannot achieve. Not in any way, shape, or form.

You just simply cannot underestimate your clients and coworkers.

IT: where you have to be nominally smarter to deal with the same stupid people.