// JavaScript Document

function checkPhonenumber( form ){ 
phonenumber = form.phonenumber.value; 
phonenumber.replace(/-| /g,'');

if (phonenumber == "") { 
document.getElementById('messageArea').innerHTML = "Geen telefoonnummer ingevuld"; 
form.phonenumber.focus(); 
return false ; 
} else if (phonenumber.length < 8 || phonenumber.length > 12) { 
document.getElementById('messageArea').innerHTML = "Ongeldig telefoonnummer ingevuld"; 
form.phonenumber.focus(); 
return false ; 
} else if (phonenumber.charAt(1) == 8){ 
document.getElementById('messageArea').innerHTML = "Geen servicenummers toegestaan"; 
form.phonenumber.focus(); 
return false ; 
} else if (phonenumber.charAt(1) == 9){ 
if (phonenumber.substring(2,4) == 91){ 
return true; 
} else { 
document.getElementById('messageArea').innerHTML = "Geen servicenummers toegestaan"; 
form.phonenumber.focus(); 
return false ; 
} 
} else if (phonenumber.charAt(0) != '+' && phonenumber.charAt(0) != 0){ 
document.getElementById('messageArea').innerHTML = "Ongeldig telefoonnummer ingevuld"; 
form.phonenumber.focus(); 
return false ; 
} else { 
document.getElementById('messageArea').innerHTML = ""; 
window.open('', 'foo', 'width=460, height=360,status=no,resizable=no,scrollbars=no'); 
return true ; 
} 
}