Ladies and Gentlemen, Please Welcome… the IE Mobile User Agent String!

Yesterday, the IE team introduced their User Agent string for IE9. We felt that it was only right that we do the same thing.

Thus, without further ado, introducing the Windows Phone Internet Explorer UA String:

Mozilla/4.0 (compatible; MSIE 7.0; Windows Phone OS 7.0; Trident/3.1; IEMobile/7.0; <DeviceManufacturer>;<DeviceModel>)

This will be the standard format of our User Agent string for Windows Phone 7 series. Some things to note:

  • The version token is MSIE 7.0, which reflects the base level of the browser
  • The platform token is now "Windows Phone OS 7.0"
  • The Trident token is 3.1, which is the rendering engine for this version
  • The Mobile Version token is IEMobile/7.0, which reflects the current version of Windows Phone Internet Explorer. This will be updated as we evolve the browser.
  • Device manufacturers will append their information to the end of the UA string, listing both the manufacturer and the model of the device.

If you have a Web site that serves rich mobile content to other browsers, please test your site with this new UA string and send us feedback. As I noted in an earlier post, the Windows Phone developer tools come pre-loaded with IE Mobile in the emulator, which you can use to test your site.

Update 6-17-10: Moved DeviceManufacturer and DeviceModel inside the comment block

Joe Marini

Principal Program Manager, Windows Phone

Comments (11)
  1. stevewebdev says:

    Many on the IE Blog are wondering what the real specs of the mobile IE browser are on the Windows Phone 7.

    This CNET article:

    indicates that the browser is somewhere between IE7 and IE8 (very vague)

    More importantly are the JavaScript fixes in IE8 going to be in the mobile version? e.g. will document.getElementById(id) actually work or is it the busted version in IE6/IE7.

    What CSS additions from IE8 are supported? e.g. -ms-filter:”alpha(opacity???)”

    Or more specifically what stuff from IE8 is NOT in the mobile version?

    The user-agent string you’ve provided above seems to indicate that this is actually a very old version of IE. (e.g. Trident/3.1)

    Please clarify as much as possible, or point out reference documentation.


  2. Hi Steve,

    Check out my session from MIX10 online, where I cover some of this (toward the second half of the talk):


    * It’s the rendering engine from IE7, with some JavaScript improvements from IE8.

    * We added only a couple of CSS improvements, like the ability to recognize -webkit-text-size-adjust (and the -ms version too).

    * There are some docs available at, and we will be updating them and adding more as we continue development throughout the coming weeks.

  3. Richard Uren says:

    Hi Joe,

    Thanks for that information on the new Browser string. We've spotted a few of those over here from Samsung, LG, ASUS & of course Microsoft.

    Given that IEMobile/7.0 references 'Windows Phone 7 Internet Explorer', how should previous IEMobile X.Y strings be referenced. For example would :-

    Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 7.11) be Windows CE Internet Explorer 7.11 ?

    Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 8.12; MSIEMobile 6.5) be Windows CE Internet Explorer 8.12 ? Or Internet Explorer Mobile 8.12 ? Or something else ?

    Thanks Joe,



  4. Hi Richard,

    I have to be honest, I'm not entirely familiar with those older UA strings. However, since they contain references to MSIE 6.0, I would say that you should not use the IEMobile portion to pinpoint the version of the browser.

    We're doing a bit of a reset on the UA string, so you essentially need to check for "Windows Phone OS" and an IEMobile/X where X is >= 7 to see if it's the modern mobile version of IE.

  5. Jesus Christ says:

    I have really hoped that you guys would use the IE9 rendering engine, so that developers did not have to create all sorts of tweeks and mods to get their webpages displaying properly. It seems extremely odd that Microsoft have spent so much time advocating for W3C standards with the IE9 browser and then release a mass market phone with an IE7-8 engine, so that developers once more can waste billions of dollars trying to make the webpages look good in every non-acid/non-w3c-complaint "***" of a browser rendering engine.

    Not mad, just disappointed.

  6. André says:

    Why does the IE Mobile not load:

    <link href="/assets/styles/foo.css" rel="stylesheet" type="text/css" media="handheld"/>


  7. @jesus: Our old method of building the mobile browser by taking the previous version and hacking it down is being phased out. You can expect to see closer releases of IE desktop and mobile in the future.

  8. @Andre I think that IE mobile 7 doesn't look at the "handheld" type. You can use conditional comments for this – I will have a post soon.

  9. Mattie says:

    Any news on the conditional comments for IE mobile 7?  Is it possible to distinguish between desktop IE7 and mobile IE7?

  10. Mattie says:

    Any news on the conditional comments for IE mobile 7?  Something that targets just the mobile IE7 and not the desktop?

  11. Stay tuned, Mattie – we'll have a post on this soon.

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