How to redirect to mobile site using htaccess

Do not redirect to your mobile site using javascript or PHP script. It wastes resources to execute the script. The right place to redirect to your mobile site is in .htaccess file. If you have proper redirect rules set up in the .htaccess file, the web server will forward the visitor to your mobile website before it executes the script.

The following set of rewrite rules will redirect all smart phone devices to a specific mobile website.

Simple Version of Rewrite Rules

# turn on rewrite engine
RewriteEngine on

# only detect smart phone devices if we are not on mobile site
# to prevent redirect looping
RewriteCond %{HTTP_HOST} !^m.mysite.com$

# a bunch of smart phone devices
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|iphone|ipod"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "iemobile|opera mobile|palmos|webos"[NC,OR]

# redirect google mobile bot
RewriteCond %{HTTP_USER_AGENT} "googlebot-mobile"[NC]

# if the request is from any one of the above devices
# redirect to mobile site
RewriteRule .? http://m.mysite.com%{REQUEST_URI}  [L,R=302]

Complete Version of Rewrite Rules

# turn on rewrite engine
RewriteEngine on

# only detect smart phone devices if we are not on mobile site
# to prevent redirect looping
RewriteCond %{HTTP_HOST} !^m.mysite.com$

# a bunch of smart phone devices
RewriteCond %{HTTP_USER_AGENT} "sony|symbian|nokia|samsung|mobile" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "windows ce|epoc|opera|mini|nitro" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "j2me|midp-|cldc-|netfront|mot" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "up\.browser|up\.link|audiovox" [NC,OR]
RewriteCond %{HTTP_USER_AGENT} "mini|nitro|j2me|midp-|cldc"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "netfront|mot|up\.browser|up\.link"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "audiovox|blackberry|ericsson,"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "panasonic|philips|sanyo|sharp|sie-"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "portalmmm|blazer|avantgo|dange"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "palm|series60|palmsource|pocketpc"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "smartphone|rover|ipaq|au-mic,"[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "alcatel|ericy|vodafone\/|wap1\."[NC,OR]
RewriteCond %{HTTP_USER_AGENT} "wap2\.|iPhone|android"[NC,OR]

# redirect google mobile bot
RewriteCond %{HTTP_USER_AGENT} "googlebot-mobile"[NC]

# if the request is from any one of the above devices
# redirect to mobile site
RewriteRule .? http://m.mysite.com%{REQUEST_URI}  [L,R=302]

Source : http://ningningwang.blogspot.com/2012/07/how-to-redirect-to-mobile-site-using.html