RewriteCond %{REQUEST_URI} !^/m/.*$
RewriteCond %{HTTP_USER_AGENT} !^.*ipad.*$ [NC]
RewriteCond %{HTTP_ACCEPT} "text\/vnd\.wap\.wml|application\/vnd\.wap\.xhtml\+xml" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "sony|symbian|nokia|samsung|mobile|windows ce|epoc|opera mini|nitro|j2me|midp-|cldc-|netfront|mot|up\.browser|up\.link|audiovox" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "blackberry|ericsson,|panasonic|philips|sanyo|sharp|sie-|portalmmm|blazer|avantgo|danger|palm|series60|palmsource|pocketpc" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "smartphone|rover|ipaq|au-mic,|alcatel|ericy|vodafone\/|wap1\.|wap2\.|iPhone|android" [NC]
RewriteCond %{REQUEST_URI} ^/$

RewriteCond %{REQUEST_URI} !^/m/.*$
RewriteCond %{HTTP_COOKIE} !.*ignoreMobi.*$ [NC]
RewriteCond %{HTTP_USER_AGENT} !^.*ipad.*$ [NC]
RewriteCond %{HTTP_ACCEPT} "text\/vnd\.wap\.wml|application\/vnd\.wap\.xhtml\+xml" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "sony|symbian|nokia|samsung|mobile|windows ce|epoc|opera mini|nitro|j2me|midp-|cldc-|netfront|mot|up\.browser|up\.link|audiovox" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "blackberry|ericsson,|panasonic|philips|sanyo|sharp|sie-|portalmmm|blazer|avantgo|danger|palm|series60|palmsource|pocketpc" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "smartphone|rover|ipaq|au-mic,|alcatel|ericy|vodafone\/|wap1\.|wap2\.|iPhone|android" [NC]
RewriteCond %{REQUEST_URI} ^/$

test

This rewrite covers most mobile devices (with few false positives). When a mobile device is detected it is redirected to /m/.

.htaccess Mobile Device Redirect

redirect, htaccess, mobile

Apache