This article is divided in two parts where I describe how to set Firefox to access mobile content online and the second part where with the help of other extensions you can further debug your applications online as if you were accessing using a mobile phone (somekind of simulation):

1. To enable your Firefox to open wap site in .Mobi format or WML you need a couple of extension:

   1. XHTML Mobile Profile - Enable .Mobi sites

   2. WMLbrowser - Enable WML wap sites
      
      
2. To enable firefox to simulate a mobile  you can install the user agent switcher extension to simulate different browsers headers.
   
   

   1. User Agent Switcher - You need a number of user agents a set up in the extension such that you can change the viewing of the site from one device to another. Find a list of user-agents I suggest you use the WURFL resource and add the user agents you need from there.

If you have any question please free to leave a message and I will answer when possible.