function isanumber(f,ind,reg,tel){
var a = document.forms[f].elements[ind].value; 
var b = document.forms[f].elements[reg].value;
var c = document.forms[f].elements[tel].value;
var d = document.forms[f].elements[tel].name;
if(!isNaN(a) && !isNaN(b) && !isNaN(c)) {
return true;
}
else{
document.forms[f].elements[ind].style.background='#FFA05F';
document.forms[f].elements[reg].style.background='#FFA05F';
document.forms[f].elements[tel].style.background='#FFA05F';
display_erreur('erreur', 'isanumber', d);
return false;
}
}