Best way to store phone numbers

[zzz]

I would like to store prone number in db which may have the following fields:

[phone] Ext. 5555

Now, the form that I have splits the input into 4 distinct groups to make it clear to user what to put in. There are a number of way it could be stored properly. For example I can just combile the values into one var and tuck it away, like:

if ($group1 != '') {
    $ext = " Ext. ".$group5;
} else {
    $ext = '';
} 

$number = "(".$group1.") " . $group2 . "-" . $group3 . $ext; 

But it seems there may be a better way of doing it. Any suggestions?

[zzz]

Nevermind, I decided to go with implode/explode.