Redirect based on user device

[creative7]

I'm looking for a way to redirect customers shopping on mobile or tablet to a specific domain

I have used the following in .htaccess but doesn't seem to work 

RewriteEngine On
# Check for mime types commonly accepted by mobile devices
RewriteCond %{HTTP_ACCEPT} "text\/vnd\.wap\.wml|application\/vnd\.wap\.xhtml\+xml" [NC]
RewriteCond %{REQUEST_URI} ^/$
RewriteRule ^ http://m.domain.com%{REQUEST_URI} [R,L]

 

Any help greatly appreciated