is it possible to assign the priority value ... more than 10 ??
Because i have 15 priorities in my IVR
No, it's not. 1 - 10 is all we have to work with.
There is no doubt a solution to your problem, unfortunately, it's not packaged up all nice and neat, like the Set Priority step is. You will need to get creative with your scripting, and be flexible with your standard reporting package.