title: Populate the Phone Number field with the dialing code from the selected country
body: <p>Hi I'd like some help please.</p>
  
  <p>I'm having a contact form build on Bootstrap and this is the part of my code I'd like to focus on</p>
  
  <pre><code>&lt;div class="form-group"&gt;
      &lt;label for="country"&gt;* What country are you in ?&lt;/label&gt;
      &lt;select name="country" class="form-control"&gt; // list of all countries here - comes from database
          &lt;option value="uk"&gt;United Kingdom&lt;/option&gt;
          &lt;option value="gre"&gt;Greece&lt;/option&gt;
          &lt;option value="ger"&gt;Gemany&lt;/option&gt;
          &lt;option value="fra"&gt;France&lt;/option&gt;
          &lt;option value="ita"&gt;Italy&lt;/option&gt; 
      &lt;/select&gt;
  &lt;/div&gt;
  
  &lt;div class="form-group"&gt;
      &lt;label for="phone"&gt;* What’s your phone number ?&lt;/label&gt;
      &lt;input type="text" name="phone" value="" class="form-control" /&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>What I'd like to do is when I select a country from the dropdown to populate the phone field with the dialing code of the selected country. For example if I pick <code>United Kingdom</code> from the select menu then the phone field should have the +44 code at the beginning and then fill out my phone, So on the server side I should have something like this</p>
  
  <pre><code>$_POST['phone'] =&gt; +44 123456
  </code></pre>