Bloqueando Letras ou Numeros no Input

<script type="text/javascript">
function Onlynumbers(e)
{
    var tecla=new Number();
    if(window.event) {
        tecla = e.keyCode;
    }
    else if(e.which) {
        tecla = e.which;
    }
    else {
        return true;
    }
    if((tecla >= "97") && (tecla <= "122")){
        return false;
    }
}

function Onlychars(e)
{
    var tecla=new Number();
    if(window.event) {
        tecla = e.keyCode;
    }
    else if(e.which) {
        tecla = e.which;
    }
    else {
        return true;
    }
    if((tecla >= "48") && (tecla <= "57")){
        return false;
    }
}
</script>
// Nome: <input type="text" onkeypress="return Onlychars(event)">
// Telefone: <input type="text" onkeypress="return Onlynumbers(event)">