Question: What are the datatypes available in asterisk server dial plan?

how to check the date type?

Answer: 
No, in dialplan everything is a string. You can use AGI to check date or compare various things.

What exactly do you need? I'm guessing but maybe this will be useful: [How to include contexts based on time and date](http://www.voip-info.org/wiki/view/Asterisk+tips+openhours)
There is no type in dialplan, everything can be treated string variable.

But if required, you can always use your favorite programming language using AGI.