In marketing, undershot customers are those we would want more services than what is currently provided. Major software and hardware vendors do not provide each type of technical support many customers require. Working on tech support lines for many years, I have talked to many customers who were willing to pay the extra dollar to get services not offered by the vendor.
As an independent IT Consultant, you can reach many undershot customers in your local market by offering services they cannot get from the vendor or from major tech support firms. There are thousands of small business owners who are willing to hire consultants to customize their software applications; many business owners will gladly pay you to customize their e-mail applications, their MS office, their browsers, their accounting software, etc.
There are many businesses struggling with easy to fix technical problems and they are desperately looking for help.