Via the documentation of Bootstrap 2
Bootstrap doesn't include responsive features by default at this time
  as not everything needs to be responsive. Instead of encouraging
  developers to remove this feature, we figure it best to enable it as
  needed.
 How to enabling responsive features 
Turn on responsive CSS in your project by including the proper meta
  tag and additional stylesheet within the <head> of your document. If
  you've compiled Bootstrap from the Customize page, you need only
  include the meta tag.
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link href="assets/css/bootstrap-responsive.css" rel="stylesheet">
 If you don't compiled Bootstrap from the Customize page,  here is how to do it 
- Use the compiled responsive version, bootstrap-responsive.css
- Add @import "responsive.less" and recompile Bootstrap
- Modify and recompile responsive.less as a separate file
.
/* Large desktop */
@media (min-width: 1200px) { ... }
/* Portrait tablet to landscape and desktop */
@media (min-width: 768px) and (max-width: 979px) { ... }
/* Landscape phone to portrait tablet */
@media (max-width: 767px) { ... }
/* Landscape phones and down */
@media (max-width: 480px) { ... }
for more information, read the documentation. I hope this solution will help you.
 Suggestion
I think the best solution is to use bootstrap 3 it will work fine
Add those meta in your header page to tell the browser to disable the scaling. Then the CSS @media selectors are working as expected :
<meta content="True" name="HandheldFriendly">
<meta name="viewport" content="width=device-width; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;">
<meta name="viewport" content="width=device-width">
suggestion from this question