Javascript RegExp in Forms

I cannot get the result right. I write area and phone by numbers but it still gives me error

[code]
function validate_text(field,alerttext) {
with(field) {

var re = /[a-zA-Z]/g;
if(re.test(field)) { return true;}else{alert(alerttext);return false;}
}
}
function validate_number(field,alerttext){
with(field) {

var re = /[0-9]/g;
if(re.test(field)) { return true;}else{alert(alerttext);return false;}
}
}

function validateForm(thisForm){
with(thisForm)
{
if(validate_number(area,”wrong area code”) == false) {

area.focus();return false;
}
if(validate_number(phone,”wrong phone”) == false) {

phone.focus();return false;
}
if(validate_text(name_surname,”wrong name”) == false) {

name_surname.focus();return false;
}

}
}[/code]

[code]…<b>Name Surname :</b><input style=”margin-left:10px;” type=”text” name=”name_surname”/>
<br /><br />
<b>phone :</b><input type=”text” style=”margin-left:19px;” maxlength=”4″ size=”4″ name=”area” />
-<input type=”text” style=”margin-left:5px;” maxlength=”7″ size=”10″ name=”phone” /><br /><br />….[/code]

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