No. Most Free Phone Psychic Readings aren't free.
While it's true a number of them might offer a free 3 minutes, chances are you won't get the answers you seek in just 3 minutes time. So what happens after your 'free time' ends? Most often other charges kick in (and many of them are on a per minute basis) and can range anywhere from $.99 to over $10 per minute. Do the math. A 30 minute reading at $10 is $300 -- that's way too expensive.
Consider too that a number of sites offer really cheap readings for newbies, but that's only if you're new. The fine print some times states that the special pricing is for first time customers, and after that, the price goes up substantially. Are these psychic scams? Yes and no. While people are told the price in some fashion, too many people ignore it, don't look deeper at the pricing structure (aka fine print) or simply lose track of time.
Now that's not to say everyone who works for a hotline is a fraud. Even I belong to some of them. On the whole though, it's not easy to weed out the legitimate psychics from the fakers.
So how's the best way to find a phone psychic? Hire them directly. Many readers who are reputable will often refund your money after the first few minutes of your session if you feel uncomfortable. Just makes sure you ask before the end of the session, or even halfway through, since then it's too late. You come off as a scammer in that case.