I have a jQuery Mobile page that works ok in Safari on iPhone (iOS 5+). And when clicking at this link...
@Html.ActionLink(\"Click to download\", \"Download\
Your user agent (browser) doesn't support cookies or has cookies disabled. In this case ASP.NET falls to a compatibility mode in which it tracks user Sessions by appending the session id in the url. So now all your urls will have this id. It's perfectly normal behavior.
The same will happen not only with ASP.NET Session but with Forms Authentication cookies. You could disable this behavior for ASP.NET Session in web.config by forcing to always use cookies:
Obviously if the user disables cookies, your application will simply crash as it won't be able to track users. And absolutely the same goes for the forms authentication cookies: