documentclass[12pt]{article}

usepackage[cp1250]{inputenc}
usepackage{lmodern}        % for the looks
usepackage{biolinum}       % for the looks
usepackage[T1]{fontenc}

usepackage{etoolbox}
usepackage{titletoc}
usepackage[colorlinks,linktoc=none]{hyperref}


newcounter{numSubSection}
    setcounter{numSubSection}{0}

gpreto{subsection}{%
    refstepcounter{numSubSection}}%


titlecontents{section}[0pt]%
    {addvspace{6pt}sffamilybfseriesnormalsize%
        makebox[18pt][r]{%
            hyperlink{page.thecontentspage}{textbf{thecontentspage}}%
            hspace{6pt}}}%
    {makebox[30pt][r]{thecontentslabelhspace{12pt}}}%
    {makebox[30pt][r]{null}}%
    {}%


makeatletter

newlength{TOCleftSkip}
    setlength{TOCleftSkip}{66pt}%
newlength{TOCrightSkip}
    setlength{TOCrightSkip}{18pt}%

newtoggle{ifSub}
    togglefalse{ifSub}%
newtoggle{ifSection}
    toggletrue{ifSection}%
newcounter{RefSubSection}%
    setcounter{RefSubSection}{0}%
    renewcommand*theRefSubSection{@arabicc@RefSubSection}%

renewcommand*{tableofcontents}{%
    section*{contentsname}%
    addcontentsline{toc}{section}{contentsname}%
    toggletrue{ifSection}%
    setcounter{RefSubSection}{0}%
    @starttoc{toc}}%

gpreto{l@section}{%
    nottoggle{ifSection}
        {par%
            addtolength{leftskip}{-TOCleftSkip}%
            addtolength{rightskip}{-TOCrightSkip}%
            togglefalse{ifSub}}{}%
    toggletrue{ifSection}}%

renewcommand*{l@subsection}[2]{%
    stepcounter{RefSubSection}%
    toggletrue{ifSub}%
    iftoggle{ifSection}
        {togglefalse{ifSection}%
            addtolength{leftskip}{TOCleftSkip}%
            addtolength{rightskip}{TOCrightSkip}%
            noindent}%
        {unskipbegingroupupshapesmall textbullet~endgroup}%
    begingroup%
        upshapesmall#1 hyperlink{numSubSection.theRefSubSection}{textbf{#2}}%
    endgroup}%

renewcommand*{l@subsubsection}[2]{%
    iftoggle{ifSection}
        {togglefalse{ifSection}%
            addtolength{leftskip}{TOCleftSkip}%
            addtolength{rightskip}{TOCrightSkip}%
            noindent}%
        {iftoggle{ifSub}
            {togglefalse{ifSub}relax%
                unskipbegingroupupshapesmall: endgroup}%
            {unskipbegingroupitshapesmall, endgroup}}%
    begingroupitshapesmall#1endgroup}%

renewcommand*{numberline}[1]{}%

makeatother


% solution ends here, code below is just for the example
begin{document}

% Frontmatter - only unnumbered/unlabeled sections
pagenumbering{roman}
    clearpage
    tableofcontents

    clearpage
    section*{Preface}
    addcontentsline{toc}{section}{Preface}

    clearpage
    section*{Another Preface}
    addcontentsline{toc}{section}{Another Preface}


% Mainmatter - only numbered/labeled sections
    clearpage
    addtocontents{toc}{protectvspace{18pt}}       % just some separation
    pagenumbering{arabic}
    %clearpage
    section{First}
        subsection{Australia}
            subsubsection{Alpha}
            subsubsection{Beta}
            subsubsection{Charlie}
            subsubsection{Delta}
            subsubsection{Echo}
            subsubsection{Foxtrot}
        subsection{Brazil}
            subsubsection{Golf}
            subsubsection{Hotel}
            subsubsection{India}
        subsection{Canada}

    clearpage
    section{Second}

    clearpage
    section{Third}
        subsection{Denmark}
            subsubsection{Juliet}
            subsubsection{Kilo}
            subsubsection{Lima}
            subsubsection{Mike}
            subsubsection{November}
        subsection{Egypt}
            subsubsection{Oscar}
            subsubsection{Papa}
            subsubsection{Quebec}
            subsubsection{Romeo}

    clearpage
    section{Fourth}
        subsection{Georgia}
            subsubsection{Sierra}
        subsection{Haiti}
            subsubsection{Tango}
            subsubsection{Uniform}
            subsubsection{Victor}
            subsubsection{Whiskey}
        subsection{Iceland}
        subsection{Japan}
            subsubsection{X-ray}
            subsubsection{Yankee}
            subsubsection{Zulu}
            subsubsection{Alpha}
            subsubsection{Beta}
            subsubsection{Charlie}
            subsubsection{Delta}
            subsubsection{Echo}
        subsection{Kenya}
            subsubsection{Foxtrot}
        subsection{Laos}
            subsubsection{Golf}
            subsubsection{Hotel}
            subsubsection{India}
            subsubsection{Juliet}
            subsubsection{Kilo}


end{document}