I wonder where the saying Let The Buyer Be Ware came from. E-calls can make the sounds for you but there is still a learning curve for their use and a lot of people might not realize several of them. The right sounds to be played in what situations, the volume it should be played at, how long should I play it, should I start playing it then stop for a few minutes and start playing it again or just turn it on and let it play continuously. You will get some coyotes, bobcats and fox to respond with any of the calls at any time of the year or time of the day in about any location but to truly be proficient at calling you should still put time in learning about the target animals as well as the prey animals you intend to target. I will do better if I use, say female invitation calls during breeding season when a female coyote would use those sounds. If I use puppy sounds or fawn blats when there are animals of that age group around,I will have better success with them. Not a one of us were born knowing what we need to know, we all learn at our own pace and what we are most interested in learning, some of will become very proficient at some things, but not so much at others. Whatever it is that we choose to do our best at we can put the amount of money and time that we can afford too into it, while we are enjoying ourselves.