If you have not yet registered your mobile phone number, here's how:

1. At the top of the Messenger window, click the button showing a mobile device with a small arrow pointing to it.

2. Please click Set up Mobile Device.

3. Under "Register a new device," follow the steps for adding your mobile.

4. In the last step, you can choose to Automatically sign me into my mobile device when I log out by leaving the check in that box. If you don't want to be signed into your mobile device every time you sign out of Yahoo! Messenger, un-check this box.

Once you've set up a device, if you've checked the Automatically sign me in box, you'll automatically be signed into your mobile every time you sign out of Messenger, so you can get IMs anywhere you go.

If you did not check the Automatically sign me into my mobile device when I log out box when you set up your number, here's how to manually sign into your mobile:

1. Click Messenger.

2. Click Sign in to _____ (your number).

Please note: Signing in to your mobile device signs you out of Yahoo! Messenger.

If you change your mind and decide that in fact you would like to sign into your mobile automatically every time you sign out of Yahoo! Messenger, here's how:

1. At the top of the Messenger window, click the button showing a mobile device with a small arrow pointing to it.

2. Click Always sign in to _____(your number).

Remember, you need to have a strong signal and be within the coverage area to receive messages. If you are, but are still having problems sending or receiving messages, switch your phone off and back on (as a means of providing an updated "request" to the network).