I think this is how its doneFor Yahoo msnger, go to Messenger->preferences->general-> Edit mobile devicethen enter your mobile number(+91mobile number)then again go to Messenger->preferences->generaland then click on "sign in to mobile device everytime you log out"Now, when ever you wish to lig out and log onto your mobile, click on the Messenger->Sign into +91mobile numberand you will receive a msg on your mob tha tyou have signed into Yahoo msnger....I use an Aircel/RPG mobile. for me, replying to messages is free, but logging on and logging off by sending an sms, and checking who is online, costs Rs.2...