Ok, I'll take a little flak, but calling and calls are somewhat overrated in my opinion. If you are out and about around turkeys much, you'll find that they are a lot like people. Actual calls vary a great deal-some almost high and squeaky, some almost horase like they've got a cold. I hear them off and on all spring and summer and sometimes I laugh at how silly some of the old hens will sound. I think how you use your call is more important than how you sound or even the cadence of the call. I think many hunters way overcall and pay much more attention to calling than they do to not moving and being patient. If you find a tom that's hot and in the mood they just aren't that hard to call in unless you really screw up, the key is finding one and then getting hidden up before he busts you. The last few years I've taken a bird on the opening day and had the luxury of just going out fooling around with them for the rest of the season, it allows me to just observe and listen and I've learned a lot without the pressure of trying to actually shoot one. Scouting and observing their habits come way ahead of calling ability to me. Just my 
Good advice there.
When one starts putting him or her self in the mode of thinking and acting (i.e vocalizations) like a turkey, success usually follows. Add a good pinch of patience.
