Using subdomains (mobile.yourdomain.com)
Mobile Joomla! supports mobile site display through subdomains. Mobile subdomains replace www part in your domain name. For example www.yoursite.com becomes mobile.yoursite.com or m.yoursite.com.
New subdomains must be added through your hosting provider tools, like cPanel. You can configure which subdomains use which themes and templates in Mobile Joomla!, but the actual process for adding mobile.your.site.com to respond to HTTP requests is done elsewhere. Please refer to your hosting provider support for this process.
Mobile Joomla! settings page contains mapping where you can choose which themes are used for which subdomains.
For more information, see these discussion threads
