Back in 1603, a principle of contract law emerged that shifted the responsibility for discovering defects from the seller to the buyer: Caveat Emptor. If your Latin is a little rusty, this translates as “Let the Buyer Beware.”   Fast forward about five centuries, and the principle of Caveat Emptor is very much alive and well for all kinds of transactions and purchases, including when it comes to switching to a digital phone company.   Basically, the advice — and frankly, the warning — to heed is that you must conduct your due diligence BEFORE you sign on the dotted line. Otherwise, your investment...