\documentclass{article}
\usepackage{cals}
\usepackage{ptext,lipsum}
\usepackage[Kashida]{xepersian}
\begin{document}
\makeatletter
\def\cals@framecs@width{.4pt}
\def\cals@framers@width{.4pt}
\makeatother
\begin{calstable}
\colwidths{{3cm}{4cm}{5cm}}
\thead{%
این توضیح جدول است که در بالای جدول قرار می‌گیرد.
\par\bfseries
\brow\cell{ستون اول}\cell{ستون دوم}\cell{ستون سوم}\erow
}
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\begin{itemize}\item\ptext[1]\end{itemize}}\erow
\brow\cell{\ptext[1]}\cell{\ptext[1]}\cell{\ptext[1]}\erow
\tfoot{\bfseries%
\brow \cell{پایان ستون اول}\cell{پایان ستون دوم}\cell{پایان ستون سوم}\erow
\lastrule
توضیح جدول در آخر جدول.
\par
}
\end{calstable}
\end{document}