As far as I know the Nash call range is optimal against the Nash shoving range.

You should be using Nash as a guideline moreso than a decision-maker. If your opponent is playing too tight then you can shove wider than Nash suggests or you can start to min-raise/fold because you know that he won't play back at you without a hand. If you are min-raising then you need to be coming up with a hand range of your own rather than using Nash. However, in using Nash as a guideline you need to keep in mind that if you are changing some aspects of the strategy then other parts will become exploitable. For example, if you have T5ss and look at Nash, it is listed as 11.9BB. If you follow the entire Nash strategy then shoving here is unexploitable. However, if you are min-raising some hands then only shoving the weaker hands like T5ss then your play can become exploitable because they can start calling your shoves lighter and folding or cold-calling your min-raises.

Can you explain that how should I read this one? I dont understand those numbers. Example: Caller a2 shows 20+. It cant means that I have to call with 20 bb`s??

The first step is to determine how deep you want to play shove/fold against the player.

OOP, you usually don't want to use the Nash chart to make your calling decisions for you 20bb deep, as calling with A2o or A2s would usually be a bad idea (most people that shove 20bb deep don't do so very wide).

I explain it much better I believe in my Introduction to the End Game video.  You can find it in the videos > RyPac13 section of the site.  If you have any specific questions after watching that video I'm happy to help.

I think one important point to keep in mind is that the calling tables only apply to opponents who either shove or fold and not if they sometimes do other things like minraising or limping.

The idea is basically if you opponent only shoves Kings and Aces and [B]folds[/B] all other hands, then he's making a huge mistake because he's not getting these hands often enough - so the calling-ranges also work against opponents who are way too tight.

However, as soon as he's also minraising or limping some hands, the shoving part of his range gets a lot tighter - he could, for instance, be shoving exclusively Kings and Aces and limping the rest.  Against such an opponent, calling his shoves wide would be a huge mistake.

Instead, you should call a lot tighter than Nash suggests when he shoves, but instead aggressivly play back against his limps.

At the $50's and $100's, I sometimes use Nash as deep as 15-20 bb when shoving, but I'm usually very tight when calling - IMO it's fine if you're less than 7 bb deep because most opponents do shove very wide when they're that shallow, but not any deeper.

Ryan explains it very well in his Endgame video, so make sure to watch that.

Jack