(1.1) Launch Yahoo!7 Messenger on your PC. Choose Sign in to xxx.xxx.xxxx. You should see your mobile number on this menu. If not, go to How to set up.
(1.2) You‘ll get a welcome message from Yahoo!7 the first time you log into Yahoo!7 Messenger for SMS from your desktop.
Seen by your Messenger contacts
(1.3) Your Yahoo!7 Messenger contacts will see you as mobile.