function only_numbers(e) 
{
    var unicode=e.charCode? e.charCode : e.keyCode;
    if (unicode!=8 && unicode!=9) //if the key isn’t the backspace key (which we should allow) 
    { 
        if (unicode<48||unicode>57) //if not a number 
        {
            return false //disable key press 
        }
    }
}

function only_phonenumbers(e) 
{
    var unicode=e.charCode? e.charCode : e.keyCode;
    if (unicode != 8 && unicode != 9) //if the key isn’t the backspace key (which we should allow) 
    { 
        if ((unicode != 45 && unicode < 48) || unicode > 57 ) //if not a number 
        {
            return false //disable key press 
        }
    }
}